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Synthesis of alkylboronic acids and alkylboronates
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A mild Pd-catalyzed process for the borylation of primary alkyl bromides using
bis(pinacolato)diboron as a boron source tolerates a wide range of functional
groups on the alkyl bromide substrate and offers complete selectivity in the
presence of a secondary bromide. This approach has been extended to the use of
alkyl iodides and alkyl tosylates, as well as borylation reactions employing
bis(neopentyl glycolato)diboron as the boron source.
A. Joshi-Pangu, X. Ma, M. Diane, S. Iqbal, R. J. Kribs, R. Huang, C.-Y. Wang, M.
R. Biscoe, J. Org. Chem., 2012,
77, 6629-6633.
CeO2 nanorods catalyze the borylation of alkyl halides and aryl iodides with
B2pin2. A wide range of synthetically useful boronate
esters are readily obtained demonstrating broad utility and functional group
tolerance. The catalyst can be reused for up to six runs without appreciable
loss in activity.
R. Bhawar, S. Saini, K. S. Patil, D. H. Nagaraju, S. K. Bose, J. Org. Chem., 2023, 88,
16270-16279.
Very low amounts of Manganese(II) bromide and tetramethylethylenediamine (TMEDA)
catalyze the cross coupling of (bis)pinacolatodiboron with a wide range of alkyl
halides. This method allows access to primary, secondary, and tertiary boronic
esters.
T. C. Atack, S. P. Cook, J. Am. Chem. Soc., 2016,
138, 6139-6142.
The use of low-cost iron(III) acetoacetate and tetramethylethylenediamine (TMEDA)
enables a mild direct cross-coupling of alkyl halides with
bis(pinacolato)diboron at room temperature. Moreover, the borylation of benzylic
or allylic chlorides, tosylates, and mesylates is possible. The reactions show
broad functional-group compatibility.
T. C. Atack, R. M. Lecker, S. P. Cook, J. Am. Chem. Soc., 2014,
136, 9521-9523.
Electroreduction at a high current enables a fast, scalable, and transition-metal-free borylation of alkyl
halides (X = I, Br, Cl) at
room temperature. This process
provides an efficient and practical access to primary, secondary, and tertiary
boronic esters, including late-stage borylation of natural products and drug derivatives.
B. Wang, P. Peng, W. Ma, Z. Liu, C. Huang, Y. Cao, P. Hu, X. Qi, Q. Lu, J. Am. Chem. Soc.,
2021, 143, 12985-12991.
A catalyst formed in situ from NiBr2 • diglyme and a pybox ligand
accomplishes Miyaura-type borylations of unactivated tertiary, secondary, and
primary alkyl halides with diboron reagents to furnish alkylboronates. The
method exhibits good functional-group compatibility and is regiospecific.
A. S. Dudnik, G. C. Fu, J. Am. Chem. Soc., 2012,
134, 10693-10697.
The formation of electron-donor-acceptor complexes between N-alkylpyridinium
salts and bis(catecholato)diboron enables photoinduced single-electron transfer
and fragmentation to carbon-centered radicals, which are subsequently borylated.
This mild and operationally simple deaminative borylation allow a diverse range
of readily available alkylamines to be efficiently converted into synthetically
valuable alkylboronic esters under catalyst-free conditions.
J. Wu, L. He, A. Noble, V. K. Aggarwal, J. Am. Chem. Soc.,
2018,
140, 10700-10704.
A decarboxylative borylation of m-chloroperoxybenzoic acid activated
fatty acids with bis(catecholato)diboron in N,N-dimethylformamide
provides a variety of alkylboronates at room temperature.
D. Wei, T.-M. Liu, B. Zhou, B. Han,
Org. Lett., 2020, 22, 234-238.
Visible-light mediates a photochemical conversion of redox-active esters of
primary, secondary, and tertiary alkylcarboxylic acids with hypoboric acid into
the corresponding boronic esters. Quantum chemical calculations and mechanistic
considerations provide deeper insights into the mechanism of photochemical
borylation reactions.
B. Nagy, Z. Gonda, T. Földesi, P. P. Fehér, A. Stirlig, G. L. Tolnai, Z.
Novák, Org. Lett., 2024,
26, 2292-2296.
An operationally simple decarboxylative borylation reaction of readily available
aliphatic acid derivatives under additive-free visible-light photoredox
conditions provides primary and secondary alkyl boronates or tetrafluoroborates
with various functional groups. A catalytic cycle involving alkyl radical
reaction with base-activated diboron species has been proposed.
D. Hu, L. Wang, P. Li, Org. Lett.,
2017, 19, 2770-2773.
An efficient visible-light-induced decarboxylative borylation of α- and
β-amino redox-active esters with bis(catecholato)diboron, followed by
transamination with 1,8-diaminonapthalene (DANH2) provide a series of
boronamides in good yields in a one-pot procedure. The photochemical can also be
conducted under flow conditions.
A. Serafino, H. Pierre, F. Le Vaillant, J. Boutet, G. Guillamot, L. Neuville.,
G. Masson, Org. Lett., 2023, 25,
9249-9254.
Supported gold catalysts efficiently promote the borylation of stable C(sp3)-O
bonds of alkyl esters. The use of a disilane as an electron source and gold
nanoparticles as a single-electron transfer catalyst is the key to generating
alkyl radicals. A subsequent cross-coupling with bis(pinacolato)diboron affords
the desired alkyl boronates.
M. Doi, H. Miura, T. Shishido, Org. Lett., 2024,
26, 2902-2907.
Cu-catalyzed formal hydroboration of terminal or 1,1-disubstituted alkenes with
bis(pinacolato)diboron and methanol provides products with exceptional
regiocontrol favoring the branched isomer. Subsequent photocatalytic
cross-couplings using iridium and nickel cocatalysis enable a highly
regioselective hydroarylation of terminal alkenes.
H. A. Kerchner, J. Montgomery, Org. Lett.,
2016, 18, 5760-5763.
An asymmetric nickel-catalyzed borylative coupling of terminal alkenes with
nonactivated alkyl halides provides a broad range of chiral boronic esters with
high regio- and enantioselectivity under mild reaction conditions. The success
of this three-component strategy is ascribed to the application of a chiral
anionic bisoxazoline ligand.
Z. Li, H. Shi, X. Chen, L. Peng, Y. Li, G. Yin, J. Am. Chem. Soc.,
2023, 145, 13603-13614.
AgOAc catalyzes an anti-Markovnikov
hydroboration of alkenes, 1,3-dienes, and alkynes with pinacolborane (HBpin).
This strategy provides an various alkyl-, allyl-, and (E)-alkenylboronate
esters regio- and stereoselectively in very good yields under ligand- and
base-free conditions.
Y. Wang, R. Guan, P. Sivaguru, X. Cong, X. Bi,
Org. Lett., 2019, 21, 4035-4038.
The use of hexamethyldisilazane lithium as a precatalyst enables a
lithium-promoted hydroboration of alkynes and alkenes with HBpin as the hydride
source. This method offers a remarkable substrate tolerance and good yields. The
hydroboration proceeds through in situ-formed BH3 driving the
turnover of the hydroboration of alkynes and alkenes.
J. Liu, C. Wu, T. Hu, W. Yang, Y. Xie, Y. Shi, Q. Li, Y. Shao, F. Zhang, J. Org. Chem., 2022, 87,
3442-3452.
Simple, commercially available borane adducts, H3BˇTHF and H3BˇSMe2
catalyse a highly regioselective hydroboration of terminal alkynes and alkenes
with pinacolborane to give linear boronic esters. The reaction tolerates ester,
amine, ether and halide substituents. This catalytic process shows comparable
reactivity to transition-metal-catalysed hydroboration protocols.
N. W. J. Ang, C. S. Buettner, S. Docherty, A. Bismuto, J. R. Carney, J. H.
Docherty, M. J. Cowley, S. P. Thomas, Synthesis, 2018, 50,
803-808.
Counterion dissociation enabled earth-abundant metal catalysis of alkene
hydroboration. Commercially available iron and cobalt tetrafluoroborate salts
were found to catalyze the hydroboration of aryl and alkyl alkenes with good
functional group tolerance.
R. Agahi, A. J. Challinor, N. B. Carter, S. P. Thomas, Org. Lett., 2019, 21,
993-997.
Bench-stable 1,8-diaminonaphthalene-protected diboronic acid (B2(dan)2)
can be used for Cu-catalyzed borylation of styrene derivatives.
The reactions proceeded in good yields in a highly selective manner.
T. Yasuda, Y. Yoshigoe, S. Saito, Org. Lett., 2023, 25,
2093-2097.
Borylation of primary and secondary alkyl chlorides, bromides, and iodides
with diboron proceeded in the presence of copper(I)/Xantphos as catalyst and a
stoichiometric amount of K(O-t-Bu) as base. Menthyl halides afforded the
corresponding borylation product with excellent diastereoselectivity, whereas (R)-2-bromo-5-phenylpentane
gave a racemic product.
H. Ito, K. Kubota, Org. Lett., 2012,
14, 890-893.
Aliphatic, aromatic, heteroaromatic, vinyl, or allylic Grignard reagents react
with pinacolborane at ambient temperature in tetrahydrofuran to afford the
corresponding pinacolboronates. The initially formed dialkoxy alkylborohydride
intermediate quickly eliminates hydridomagnesium bromide and affords the product
boronic ester in very good yield. This reaction also can be carried out under
Barbier conditions.
J. W. Clary, T. J. Rettenmaier, R. Snelling, W. Bryks, J. Banwell, W. T. Wipke,
B. Singaram, J. Org. Chem., 2011,
76, 9602-9610.
Hydroboration of terminal and internal aliphatic alkenes with
pinacolborane was carried out at room temperature in the presence of dppm and [Ir(cod)Cl]2 resulting in addition of the boron atom to the terminal carbon with a selectivity of more than
99%. A complex
prepared from dppe and [Ir(cod)Cl]2 resulted in the best yields for
vinylarenes.
Y. Yamamoto, R. Fujikawa, T. Umemoto, N. Miyaura, Tetrahedron,
2004,
60, 10695-10700.
A transition-metal-free reaction of alkyl sulfonylhydrazones with alkyl
boronic acids provides C(sp3)-rich and sterically hindered alkyl
boron reagents in a practical and modular manner. The reaction offers broad
generality and functional group tolerance.
Y. Yang, J. Tsien, A. B. David, J. M. E. Hughes, R. R. Merchant, T. Qin, J. Am. Chem. Soc.,
2021, 143, 471-480.
An efficient hydroboration of aliphatic
1,1-disubstituted alkenes with pinacolborane using a chiral phosphine-Cu catalyst
provides enantiomerically enriched β-chiral alkyl pinacolboronates from a range
of 1,1-disubstituted alkenes with high enantioselectivity.
W. J. Jang, S. M. Song, J. H. Moon, J. Y. Lee, J. Yun, J. Am. Chem. Soc., 2017,
139, 13660-13663.
A novel chiral iminopyridine oxazoline (IPO) ligand enables a highly regio- and
enantioselective iron-catalyzed anti-Markovnikov hydroboration of
1,1-disubstituted aryl alkenes. This distinct class of reactive IPO ligands will
likely be of high value for a large variety of asymmetric transformations using
first-row transition metals.
J. Chen, T. Xi, Z. Lu, Org. Lett.,
2014,
16, 6452-6455.
A Ni-catalyzed arylboration converts substituted alkenes, aryl bromides, and
diboron reagents to products that contain a tertiary or quaternary carbon and a
synthetically versatile carbon-boron bond with control of stereoselectivity and
regioselectivity. In addition, the method is useful for the
synthesis of saturated nitrogen heterocycles.
S. R. Sardini, A. L. Lambright, G. L. Trammel, H. M. Omer, P. Liu, M. K.
Brown, J. Am. Chem. Soc.,
2019,
141, 9391-9400.
An efficient ligand-free copper-catalyzed borylation offers
Markovnikov-selectivity in the reaction of bis(pinacolato)diboron with allyl
arenes, while the regioselectivity is completely opposite when styrene
derivatives are used as substrates.
Y. Wen, J. Xie, C. Deng, C. Li, J. Org. Chem.,
2015,
80, 4142-4147.
An efficient ligand-free copper-catalyzed borylation offers
Markovnikov-selectivity in the reaction of bis(pinacolato)diboron with allyl
arenes, while the regioselectivity is completely opposite when styrene
derivatives are used as substrates.
Y. Wen, J. Xie, C. Deng, C. Li, J. Org. Chem.,
2015,
80, 4142-4147.
A cobalt-catalyzed [4,3]-hydroboration of 1,3-dienes with HBPin provides
nearly enantiopure homoallylic boronate esters. A cationic cobalt(I) complex of
(R,R)-MeO-BIBOP is a very efficient catalyst while also providing
excellent regioselectivities and enantioselectivities for a broad range of
substrates.
M. M. Parsutkar, S. Bhunia, M. Majumder, R. F. Lalisse, C. M. Hadad, T.V.
RajanBabu, J. Am. Chem. Soc.,
2023, 145, 7462-7481.
Cobalt complexes generated from Co(acac)2 and bisphosphine
ligands catalyze asymmetric hydroboration reactions of
fluoroalkyl-substituted terminal alkenes with pinacolborane (HBpin) to afford the corresponding chiral
alkylboronates containing fluoroalkyl-substituted stereogenic carbon centers
with high enantioselectivity.
M. Hu, B. B. Tan, S. Ge, J. Am. Chem. Soc.,
2022, 144, 15333-15338.
A nickel-catalyzed 1,2-arylboration of vinylarenes with aryl halides provides
various 2-boryl-1,1-diarylalkanes, which constitute a class of significant
pharmacophores, in the presence of bis(pinacolato)diboron under mild reaction
conditions. This three-component cascade reaction exhibits good functional
group tolerance and excellent chemo- and stereoselectivity.
W. Wang, C. Ding, H. Pang, G. Yin,
Org. Lett., 2019, 21, 3968-3971.
A mild, efficient, highly regio- and enantioselective copper-catalyzed
hydroboration of 1,1-diaryl substituted alkenes with bis(pinacolato)diboron
provides a series of valuable β,β-diaryl substituted boronic esters with high
enantiomeric purity. Moreover, this approach is also be suitable for
hydroboration of α-alkyl styrenes for the synthesis of enantioenriched
β,β-arylalkyl substituted boronic esters.
Z. Wang, X. He, R. Zhang, G. Zhang, G. Xu, Q. Zhang, T. Xiong, Q. Zhang, Org. Lett.,
2017, 19, 3067-3070.
A very active cobalt catalyst enables a facile anti-Markovnikov hydroboration of
sterically hindered terminal alkenes. Notably, these hydroboration reactions
proceed in neat substrates at 23°C. With internal olefins, the cobalt catalyst
provides a convenient method for hydrofunctionalization of remote C-H bonds by
placing the boron substituent exclusively at the terminal positions of an alkyl
chain.
J. V. Obligacion, P. J. Chirik, J. Am. Chem. Soc., 2013,
135, 19107-19110.
Highly Selective Bis(imino)pyridine Iron-Catalyzed Alkene Hydroboration
J. V. Obligacion, P. J. Chirik, Org. Lett., 2013,
15, 2680-2683.
Efficient and site selective boron-copper addition processes involving acyclic
and cyclic disubstituted aryl olefins are promoted with a readily available N-heterocyclic
carbene (NHC) complex. In situ protonation of the C-Cu bond in the presence of
MeOH leads to efficient catalyst turnover, constituting a net Cu-catalyzed
hydroboration process.
Y. Lee, A. H. Hoveyda, J. Am. Chem. Soc., 2008,
131, 3160-3161.
Cobalt complexes of iminopyridine-oxazoline (IPO) ligands can be applied to the
asymmetric hydroboration of 1,1-disubstituted aryl alkenes to afford
α-alkyl-β-pinacolatoboranes with exclusive regioselectivity in high yields with
up to 99.5% ee. An efficient synthesis of naproxen is described.
L. Zhang, Z. Zuo, X. Wan, Z. Huang,
J. Am. Chem. Soc., 2014,
136, 15501-15504.
A simple protocol for the borylation of alkenes with use of impregnated copper
on magnetite showed a very broad scope. All type of olefins could be used with
similar results. The catalyst can be magnetically removed and reused several
times, showing similar activity.
R. Cano, D. J. Ramón, M. Yus, J. Org. Chem., 2010,
75, 3458-3460.
Arylboration of vinylarenes and methyl crotonate with aryl halides and
bis(pinacolato)diboron by cooperative Pd/Cu catalysis gives
2-boryl-1,1-diarylethanes and α-aryl-β-boryl ester in a regioselective manner.
The reaction is compatible with various functionalities and can be scaled-up to
a gram scale.
K. Semba, Y. Nakao, J. Am. Chem. Soc., 2014,
136, 7567-7570.
An enantioselective Cu-catalyzed borylative cross-coupling reaction of alkenes,
bis(pinacolato)diboron, and methyl iodide provides the desired methylboration
products with excellent diastereoselectivities and enantioselectivities.
B. Chen, P. Cao, Y. Liao, M. Wang, J. Liao, Org. Lett.,
2018, 20, 1346-1349.
Reduced cobalt catalysts effect selective 1,2-, 1,4-, or 4,3-additions of
pinacolborane to various 1,3-dienes depending on the ligands chosen. Regio- and
enantioselective 1,2-hydroborations of 2-substituted 1,3-dienes are best
accomplished using a catalyst prepared via activation of a chiral
phosphinooxazoline-cobalt(II) complex with zinc and NaBARF.
K. Duvvuri, K. R. Dewese, M. M. Parsutkar, S. M. Jing, M. M. Mehta, J.
Galluci, T. V. RajanBabu, J. Am. Chem. Soc.,
2019,
141, 7365-7375.
A convenient method for the synthesis of 1,1-diboronates from the corresponding
N-tosylhydrazones is also applicable to 1-silyl-1-boron compounds.
Derivatization and consecutive Pd-catalyzed cross-coupling reactions with
1,1-boronates were also explored, demonstrating the synthetic potential of
1,1-diboronates.
H. Li, X. Shangguan, Z. Zhang, S. Huang, Y. Zhang, J. Wang, Org. Lett., 2014,
16, 448-451.
(E)- and (Z)-silyl and aryl-subsituted homoallylic
methanesulfonates were converted to the corresponding cis- and trans-1-silyl-2-borylcyclobutanes
as well as 1-phenyl-2-borylcyclobutanes in the presence of a CuCl/dppp catalyst,
bis(pinacolato)diboron, and K(O-t-Bu)in THF. Stereospecific
derivatizations of the cis- and trans-borylcyclobutanes were
carried out to demonstrate the utility of the borylcyclobutanes.
H. Ito, T. Toyoda, M. Sawamura, J. Am. Chem. Soc., 2010,
132, 5990-5992.
Highly strained bicyclo[1.1.0]butyl boronate complexes, which were prepared
by reacting boronic esters with bicyclo[1.1.0]butyl lithium, react with a wide
range of electrophiles to form a diverse set of 1,1,3-trisubstituted
cyclobutanes with high diastereoselectivity via difunctionalization of the
strained central C-C σ-bond of the bicyclo[1.1.0]butyl unit.
S. H. Bennett, A. Fawcett, E. H. Denton, T. Biberger, V. Fasano, N. Winter,
V. K. Aggarwal, J. Am. Chem. Soc.,
2020, 142, 16766-16775.
The use of N-oxides in butanol as solvent enables a site-selective
oxidation of vicinal bis(boronates) with good efficiency and selectivity across
a range of substrates to provide 2-hydro-1-boronic esters, which are shown to be
versatile intermediates in the synthesis of chiral building blocks.
L. Yan, J. P. Morken,
Org. Lett., 2019, 21, 3760-3763.
Bidentate Oxazoline-substituted imidazolium salts based on [2.2]paracyclophane
with planar and central chirality can be used as ligand in Cu(I)-catalyzed
asymmetric β-boration of α,β-unsaturated esters, giving the desired products in
high enantioselectivities and yields.
Z. Niu, J. Chen, Z. Chen, M. Ma, C. Song, Y. Ma, J. Org. Chem.,
2015,
80, 602-608.
Cobalt catalysis enables mild reaction conditions for efficient and highly
regio- and enantioselective hydroboration of α-alkyl- and α-aryl- acrylates,
giving β-borylated propionates. These intermediates could serve as valuable
chiral synthons, some from feedstock carbon sources, for the synthesis of
propionate-bearing motifs including polyketides and related molecules.
M. D. Patil, K. K. Ghosh, T. V. RajanBabu, J. Am. Chem. Soc.,
2024, 146, 6604-6617.
An unprecedented nickel-catalyzed reductive borylation of enaminones provides
β-ketone boronic esters via a challenging transformation of an alkenyl C(sp2)-N
bond. While B2pin2 plays a dual role in this process,
water serves as the hydrogen source.
X. Li, Z. Chen, Y. Liu, N. Luo, W. Chen, C. Liu, F. Yu, J. Huang, J. Org. Chem., 2022, 87,
10349-10358.
An enantioselective copper-catalyzed borylacylation of aryl olefins with
acyl chlorides and bis-(pinacolato)diboron proceeds
with a 2 mol % catalyst loading and is generally completed within 30 min at room
temperature. The resulting
chiral β-borylated ketones are versatile intermediates in organic synthesis.
Z. Yang, P. Li, H. Lu, G. Li, J. Org. Chem., 2021, 86,
4616-4624.
Cu[(S)-(R)-ppfa]Cl and AgNTf2 as catalyst enable an
asymmetric conjugate addition of B2pin2 onto
α-functionalized α,β-unsaturated carbonyl compounds under mild, neutral
conditions in the presence of an alcohol. AgNTf2 and alcohols play
crucial roles for achieving high catalytic activity and enantio- and
diastereoselectivity.
J.-B. Xie, S. Lin, S. Qiao, G. Li, Org. Lett.,
2016, 18, 3926-3929.
Using bis(pinacolato)diboron, catalytic amounts of CuII, and various
amine bases in water under atmospheric conditions at rt, acyclic and cyclic
α,β-unsaturated ketones and esters are β-borylated in good yield. Mechanistic
investigations suggest that the role of the amine is not only to coordinate to
CuII but also to activate a nucleophilic water molecule to form a
reactive sp2-sp3 diboron complex.
S. B. Thorpe, J. A. Calderone, W. L. Santos, Org. Lett., 2012,
14, 1918-1921.
A simple protocol for the borylation of alkenes with use of impregnated copper
on magnetite showed a very broad scope. All type of olefins could be used with
similar results. The catalyst can be magnetically removed and reused several
times, showing similar activity
R. Cano, D. J. Ramón, M. Yus, J. Org. Chem., 2010,
75, 3458-3460.
A copper(I)-chiral secondary diamine complex catalyzes an enantioselective
conjugate boration of β,β-disubstituted enones in high yields and up to 99% ee.
The resulting chiral tertiary organoboronates can be converted to
enantiomerically enriched β-hydroxy ketones without any racemization.
I-H. Chen, M. Kanai, M. Shibasaki, Org. Lett., 2010,
12, 4098-4101.
A N-heterocyclic carbene (NHC) copper(I) complex generated in situ by the
reaction of Cu2O and a planar and centrally chiral bicyclic
1,2,4-triazolium salt was an efficient catalyst for the asymmetric β-boration of
acyclic enones, producing β-boryl ketones in high yields and
enantioselectivities.
L. Zhao, Y. Ma, F. He, W. Duan, J. Chen, C. Song, J. Org. Chem., 2013,
78, 1677-1681.
A new planar and central chiral bicyclic triazolium ligand enables a highly
efficient copper-catalyzed asymmetric conjugate boration. This protocol gave
various chiral secondary alkylboronates in very good ee. A preliminary
mechanistic study supports the bifunctional nature of the catalyst.
L. Zaho, Y. Ma, W. Duang, F. He, J. Chen, S. Soung, Org. Lett., 2012,
14, 5780-5783.
Regioselective copper-catalyzed boracarboxylation of vinyl arenes with
bis(pinacolato)diboron and carbon dioxide provides boron-functionalized α-aryl
carboxylic acids in good yields. The synthetic utility of the transformation was
shown through subsequent derivatization of the carbon-boron bond yielding formal
hydroxy- and fluorocarboxylation products as well as anionic
difluoroboralactones.
T. W. Butcher, E. J. McClain, T. G. Hamilton, T. M. Perrone, K. M. Kroner, G. C.
Donohoe, N. G Akhmedov, J. L. Petersen, B. V. Popp, Org. Lett.,
2016, 18, 6428-6431.
A catalytic enantioselective conjugate boration of β-substituted cyclic enones
in the presence of a QuinoxP*-CuOtBu complex produced enantiomerically
enriched tertiary organoboronates. The substrate scope was broad, and high
enantioselectivity was produced using both β-aromatic and aliphatic (linear and
branched)-substituted cyclic enones with five- to seven-membered ring sizes.
I-H. Chen, L. Yin, W. Itano, M. Kanai, M. Shibasaki, J. Am. Chem. Soc., 2009,
131, 11284-11285.
(η6-mes)IrBpin3 or [Ir(COD)OMe]2 catalyzes the
borylation of cyclopropanes in the presence of the phenanthroline derivative
2,9-Me2phenanthroline as ligand. The borylation occurs selectively at
the methylene C-H bonds of the cyclopropane ring in high diasteroselectivities.
The cyclopropylboronate esters can be converted to trifluoroborate salts,
boronic acids, cyclopropylarenes, cyclopropylamines, and cyclopropanols.
C. W. Liskey, J. F. Hartwig, J. Am. Chem. Soc., 2013,
135, 3375-3378.
A (NHC)AgCl complex catalyzes an efficient hydroborylation of cyclopropenes
with B2pin2, delivering a variety of cyclopropylboronates
in a stereoselective manner under mild reaction conditions. The
cyclopropylboronates can easily be transformed into functionalized
cyclopropanes.
M. Huang, C. Zhou, K.-F. Yang, Z. Li, G.-Q. Lai, P. Zhang, J. Org. Chem., 2023, 88,
13838-13846.
Rhodium-catalyzed asymmetric hydroboration of 3,3-disubstituted cyclopropenes
gave 2,2-disubstituted cyclopropyl boronates with high degrees of diastereo- and
enantioselectivity. Suzuki cross-coupling reaction of selected
cyclopropylboronic derivatives produced corresponding optically active aryl- and
vinylcyclopropanes in good yields.
M. Rubina, M. Rubin, V. Gevorgyan, J. Am. Chem. Soc., 2003,
125, 7198-7199.
A dramatic rate acceleration in the copper-catalyzed addition of bis(pinacolato)diboron
to α,β-unsaturated carbonyl
compounds was realized by adding alcohol additives. Various α,β-unsaturated carbonyl compounds
were reacted to the corresponding β-boryl carbonyl compounds in high
yields.
R. Varala, S. Nuvula, S. R. Adapa, J. Org. Chem., 2006,
71, 8283-8286.
A nickel catalyst system enables the β-boration of di-, tri-, and
tetrasubstituted α,β-unsaturated esters and amides with bis(pinacolato)diboron
in good yields.
K. Hirano, H. Yorimitsu, K. Oshima, Org. Lett., 2007,
9, 5031-5033.
Aryl cyclopropyl ketones undergo nickel-catalyzed borylative ring opening with
bis(pinacolato)diboron to yield 4-oxoalkylboronates in good yield.
Y. Sumida, H. Yorimitsu, K. Oshima, J. Org. Chem., 2009,
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In a catalytic enantioselective nucleophilic borylation, a series of aldehydes
reacted with B2pin2 in the presence of a copper(I)/DTBM-SEGPHOS
complex as catalyst and MeOH as a proton source to give the corresponding
optically active α-alkoxyorganoboronate esters with excellent
enantioselectivities. These products can readily be converted to chiral alcohol
derivatives through stereospecific C-C bond forming reactions.
K. Kubota, E. Yamamoto, H. Ito, J. Am. Chem. Soc., 2015,
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A highly efficient deoxygenative haloboration of aldehydes provides secondary
α-haloboronates. Even tertiary α-haloboronates can be readily prepared via the
same strategy with ketones. Furthermore, enantioselective chloroboration of
carbonyls was successfully achieved to give chiral secondary or tertiary
α-chloroboronates.
D. Wang, J. Zhou, Z. Hu, T. Xu, J. Am. Chem. Soc.,
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Visible-light-induced B-H insertions of HBpin with acylsilane proceed in an atom-economical, metal-free,
and operationally simple way with broad
substrate scope under mild reaction conditions, to provide important
α-alkoxyorganoboronate esters in quantitative yields.
J.-H. Ye, L. Quach, T. Paulisch, F. Glorius, J. Am. Chem. Soc.,
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Diboration of ketones with (ICy)CuOt-Bu as catalyst provides access to
various tertiary α-hydroxyboronate esters. The catalyst was generated in situ
with (ICy)CuCl and NaOt-Bu to afford a more efficient catalyst than the
preformed (ICy)CuOt-Bu. Treatment of the resulting products with silica
gel affords the corresponding α-hydroxyboronate esters.
M. L. McIntosh, C. M. Moore, T. B. Clark, Org. Lett., 2010,
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A Cu-catalyzed regioselective and stereospecific aminoboration of styrenes with
bis(pinacolato)diboron and O-benzoyl-N,N-dialkylhydroxylamines
delivers β-aminoalkylboranes in good yields. The Cu catalysis enables
introduction of both amine and boron moieties to C-C double bonds simultaneously
in a syn fashion. Moreover, the use of a chiral biphosphine ligand, (S,S)-Me-Duphos,
provides optically active β-aminoalkylboranes.
N. Matsuda, K. Hirano, T. Satoh, M. Miura, J. Am. Chem. Soc., 2013,
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Hydroboration of α,β-unsaturated carbonyl substrates followed by
1,2-elimination provides gem-difluoroalkenes under mild conditions.
gem-Difluoroalkenes can be converted into β-CF2H- and β-CFH2-α,β-unsaturated
carbonyls.
S. An, J. Zhang, G. Jiang, Synlett, 2021,
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A catalytic enantioselective diboration of vinyl boronate esters furnishes
chiral tris(boronates). Subsequent intermolecular or intramolecular deborylative
alkylation occurs in a diastereoselective fashion.
J. R. Coombs, L. Zhang, J. P. Morken,
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A Co(I)-catalyzed, selective preparation of 1,1,1-tris(boronates) from vinylarenes and
bis(pinacolato)diboron occurs at ambient temperature
with excellent selectivity, high yields, and good functional group tolerance via
double dehydrogenative
borylations to generate an 1,1-diborylalkene intermediate followed by a
hydroboration with pinacolborane formed in situ to yield the desired 1,1,1-tris(boronate).
L. Zhang, Z. Huang, J. Am. Chem. Soc., 2015,
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An Ir-catalyzed enantioselective C(sp3)-H borylation of
cyclopropanecarboxamides using a chiral bidentate boryl ligand provides β-borylated products with good to
excellent enantioselectivities. The borylated
products can be used as versatile precursors.
Y. Shi, Q. Gao, S. Xu, J. Am. Chem. Soc.,
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Related
The reaction of 1,1-bis(pinacolboronate) esters with alkyl halides promoted by
metal alkoxides provides organoboronate compounds via alkoxide-induced
deborylation and generation of a boron-stabilized carbanion.
K. Hong, X. Liu, J. P. Morken, J. Am. Chem. Soc., 2014,
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A nickel-catalyzed Negishi cross-coupling of alkyl halides, including
unactivated tertiary halides, with the boron-stabilized organozinc reagent
BpinCH2ZnI provides versatile organoboron products with high
functional-group tolerance.
P. Guo, H. Jin, J. Han, L. Xu, P. Li, M. Zhan, Org. Lett., 2023, 25,
1246-1251.
A copper-catalyzed regio- and enantioselective hydroallylation of alkenyl
boronates and boramides with allylic phosphates in the presence of hydrosilanes
enables an efficient synthesis of a broad range of homoallylic alkylboron
compounds in good yields and with high enantioselectivities.
J. T. Han, W. J. Jang, N. Kim, J. Yun, J. Am. Chem. Soc., 2016,
138, 15146-15149.
A Ni-catalyzed reductive allylation of α-chloroboronates with allyl sulfones
efficiently provides the corresponding homoallylic boronates, which could be
readily converted into valuable homoallylic alcohols or amines or
1,4-diboronates. This reaction features a broad substrate scope with good
functional group compatibility.
Y. Lou, J. Qiu, K. Yang, F. Zhang, C. Wang, Q. Song, Org. Lett., 2021, 23,
4564-4569.
In the presence of IMes-Cu catalyst, a tandem hydrocupration/allylation of
alkenyl boronates with allyl phosphate efficiently proceeds in the presence of a
hydrosilane via in situ generated Β-α-copper intermediates. Mono- and
disubstituted alkenyl boronates were effective in the reaction with terminal
allyl phosphates, but trisubstituted substrates showed limited reactivity.
W. J. Jang, J. T. Han, J. Yun, Synthesis, 2017,
49, 4753-4758.
In a Cu/(NHC)-catalyzed SN2'-selective substitution reaction of
allylic electrophiles with gem-diborylalkanes, differently substituted
gem-diborylalkanes and allylic electrophiles can be employed, and various
synthetic valuable functional groups are tolerated. The use of chiral N-heterocyclic
carbene (NHC) ligands enables an asymmetric version.
Z.-Q. Zhang, B. Zhang, X. Lu, J.-H. Liu, X.-Y. Lu, B. Xiao, Y. Fu, Org. Lett., 2016, 18,
952-955.
An iridium-catalyzed enantioconvergent coupling of the versatile
boron-stabilized organozinc reagent BpinCH2ZnI with racemic branched
allylic carbonates provides various chiral homoallylic organoboronic esters in
good yields with excellent enantioselectivities. The homoallylboronates can
easily be converted to other useful families of compounds.
P. Guo, M. Zhan, J. Org. Chem., 2021, 86,
9905-9913.
The Suzuki-Miyaura cross-coupling reaction between a diborylmethane derivative
and allyl halides or benzyl halides proceeded efficiently in the presence of an
appropriate Pd-catalyst at room temperature. The present approach provides
functionalized homoallylboronates and alkylboronates with excellent regio- and
chemoselectivities.
K. Endo, T. Ohkubo, T. Ishioka, T. Shibata, J. Org. Chem., 2012,
77, 4826-4831.
The combination of copper(I) bromide and
H8-BINOL derived phosphoramidite ligand catalyzes an enatiotopic-group-selective allylation of
gem-diborylalkanes with allyl bromides to provide enantioenriched homoallylic
boronate esters in good yields with high enantiomeric ratios under mild
conditions.
M. Kim, B. Park, M. Shin, S. Kim, J. Kim, M.-H. Baik, S. H. Cho, J. Am. Chem. Soc.,
2021, 143, 1069-1077.
The Suzuki-Miyaura cross-coupling reaction between a diborylmethane derivative
and allyl halides or benzyl halides proceeded efficiently in the presence of an
appropriate Pd-catalyst at room temperature. The present approach provides
functionalized homoallylboronates and alkylboronates with excellent regio- and
chemoselectivities.
K. Endo, T. Ohkubo, T. Ishioka, T. Shibata, J. Org. Chem., 2012,
77, 4826-4831.
A general method for accessing sterically encumbered geminal bis(boronates) is
based on a formal umpolung strategy. Readily available 1,1-diborylalkanes were
first converted into the corresponding α-halogenated derivatives, which then
serve as electrophilic components, undergoing a formal substitution with a
diverse array of nucleophiles to form a series of C−C, C−O, C−S, and C−N bonds.
P.-F. Ning, Y. Wei, X.-Y. Chen, Y.-F. Yang, F.-C. Gao, K. Hong, Angew. Chem.
Int. Ed., 2023, 62,
e202315232.
A transition metal-free deborylative cyclization of geminal bis(boronates)
bearing a leaving group provides cyclopropylboronates with high
diastereoselectivity. When derivatives of optically active epoxides were used as
the starting materials, enantioenriched cyclopropylboronates could be
efficiently prepared.
X.-Y. Chen, F.-C. Gao, P.-F. Ning, Y. Wei, K. Hong, Angew.
Chem. Int. Ed., 2023, 62,
e202302638.
A transition metal-free deborylative cyclization of geminal bis(boronates)
bearing a leaving group provides cyclopropylboronates with high
diastereoselectivity. When derivatives of optically active epoxides were used as
the starting materials, enantioenriched cyclopropylboronates could be
efficiently prepared.
X.-Y. Chen, F.-C. Gao, P.-F. Ning, Y. Wei, K. Hong, Angew.
Chem. Int. Ed., 2023, 62,
e202302638.
1,2-Bis-boronic esters are versatile intermediates that enable the rapid
elaboration of simple alkene precursors. A photoredox-catalyzed mono-deboronation generates primary β-boryl radicals that
undergo rapid 1,2-boron shift to form thermodynamically favored secondary
radicals, allowing for selective transformation of the more hindered boronic
ester.
D. Kaiser, A. Noble, V. Fasano, V. K. Aggarwal, J. Am. Chem. Soc.,
2019, 141, 14104-14109.