Categories: C-B Bond Formation > Synthesis of boronic acids and boronates >
Synthesis of vinylboronic acids and vinylboronates
Related |
Name Reactions
Recent Literature
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.
Tropylium salts promote the hydroboration reaction of alkynes to provide a
broad range of vinylboronates. Similar metal-free hydroboration reactions of
alkenes and epoxides can also be efficiently catalyzed by the same tropylium
catalysts. Experimental studies and DFT calculations suggested that the reaction
is triggered by the hydride abstraction of pinacolborane with tropylium ion.
N. N. H. Ton, B. K. Mai, T. V. Nguyen, J. Org. Chem., 2021, 86,
9117-9133.
Carboxylic acids are able to catalyze the direct hydroboration of various
terminal and internal alkynes with pinacolborane without using any metal
catalysts. This hydroboration exhibits a broad functional groups compatibility
and gives the corresponding alkenyl diboronates and monoboronates in very good
yields with exclusive regio- and stereoselectivities.
H. E. Ho, M. Asao, Y. Yamamoto, T. Jin, Org. Lett.,
2014,
16, 4670-4673.
An iron complex bearing a pyrrolide-based PNP pincer ligand enables a catalyzed
hydroboration of alkynes with pinacolborane, where the corresponding E-isomers
are obtained selectively.
K. Nakajima, T. Kato, Y. Nishibayashi, Org. Lett.,
2017, 19, 4323-4326.
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.
Simple, commercially available borane adducts, H3B·THF and H3B·SMe2
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.
A conjugated bis-guanidinate (CBG)-supported aluminum dihydride complex
catalyzes a chemoselective hydroboration of various nitriles and alkynes. The
reaction leaves other reducible groups intact. Moreover, aluminum-catalyzed
hydroboration is expanded to more challenging substrates such as alkene,
pyridine, imine, carbodiimide, and isocyanides.
N. Sarkar, S. Bera, S. Nembenna, J. Org. Chem., 2020, 85,
4999-5009.
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.
Methylpentanediolborane can be prepared easily by reaction of hexyleneglycol
with borane dimethylsulfide or B2H6 generated from NaBH4
and I2. MPBH hydroborates stereo- and regioselectively highly
functionalized alkynes. MPBH compares favorably with pinacolborane in terms of
reactivity. The obtained vinylboronic esters are air- and chromatography-stable.
N. PraveenGanesh, S. d'Hondt, P. Y. Chavant, J. Org. Chem., 2007,
72, 4510-4514.
Preparation of (E)-1-Alkenylboronic Acid Pinacol Esters via Transfer of
Alkenyl Group from Boron to Boron
K. Shirakawa, A. Arase, M. Hoshi, Synthesis,
2004,
1814-1820.
A ruthenium hydride pincer complex catalyzes the anti-Markovnikov
addition of pinacolborane to terminal alkynes yielding Z-vinylboronates
at mild conditions. The catalytic cycle involves rearrangement of coordinated
alkyne to Z-vinylidene as a key step for the apparent trans-hydroboration.
C. Gunanathan, M. Hölscher, F. Pan, W. Leitner, J. Am. Chem. Soc., 2012,
134, 14349-14352.
Ferric chloride catalyzes an efficient monoborylation of alkynes using
bis(pinacolato)diboron to provide E-vinyl boronates with high regio- and
stereoselectivity in good to excellent yields. Using iron nanoparticles, a high
catalytic activity was observed and the catalyst could be recovered simply by
using an external magnetic field. The magnetic nanoparticles were recycled six
times without any significant loss of catalytic activity.
V. S. Rawat, B. Sreedhar,
Synlett, 2014, 25, 1132-1136.
A silver(I)-N-heterocyclic carbene complex is a potent catalyst for
formal hydroboration of alkynes, providing a variety of borylalkenes with high
regio- and stereoselectivity. Under silver catalysis, allenes also undergo
regioselective hydroboration to give borylalkenes.
H. Yoshida, I. Kageyuki, K. Takaki, Org. Lett., 2014,
16, 3512-3515.
1-Alkenylboronic acid pinacol esters can be synthesized via a
palladium-catalyzed cross-coupling reaction of 1-alkenyl halides or triflates
with bis(pinacolato)diboron in toluene at 50°C in the presence of potassium
phenoxide and PdCl2(PPh3)2·2PPh3.
K. Takahashi, J. Takagi, T. Ishiyama, N. Miyaura, Chem. Lett., 2000,
126-127.
A high α-selectivity of a ligand controlled selective hydroborylation of
terminal alkynes to α-vinylboronates using a Pd catalyst can be switched to
furnish β-vinylboronates by altering the ligand from a trialkylphosphine to N-heterocyclic
carbene. Various terminal alkynes furnish the corresponding α- or
β-vinylboronates in excellent selectivity and yield.
D. P. Ojha, K. R. Prabhu, Org. Lett., 2016, 18, 432-435.
A Zr-catalyzed carboalumination of terminal alkynes followed by in situ
transmetalation with i-PrOBpin enabels an operationally simple and
scalable synthesis of trisubstituted alkenyl boronic esters in good yields, with
excellent regioselectivity and perfect stereoselectivity.
O. Zhurakovskyi, R. M. P. Dias, A. Noble, V. K. Aggarwal, Org. Lett.,
2018, 20, 3136-3139.
Reliable, operationally simple, catalytic α-selective
hydroalumination reactions proceed in the presence of diisobutylaluminum
hydride and (Ni(dppp)Cl2), and, unlike
uncatalyzed transformations, generate little or no alkynylaluminum
byproducts. The derived α-vinyl halides and boronates can be synthesized
through direct treatment with the appropriate electrophiles.
F. Gao, A. H. Hoveyda, J. Am. Chem. Soc., 2010,
132, 10961-10963.
A Pd-catalyzed direct borylation of various 1,1- and 1,2-disubstituted alkenes
provides trisubstituted alkenyl boronic esters with outstanding yields and
excellent E/Z selectivities via a boryl-Heck pathway. Several
derivatizations of the alkenyl boronic esters allow access to diverse,
stereodefined, functionalized olefins.
W. B. Reid, D. A. Watson, Org. Lett.,
2018, 20, 6822-6826.
A Cu/TEMPO catalyst system exhibits both excellent reactivity and
selectivity for the synthesis of alkenylboronates from inexpensive alkenes and
pinacol diboron. This approach enables a direct functionalization of both
aromatic and aliphatic terminal alkenes.
W. Lu, Z. Shen, Org. Lett.,
2019, 21, 142-146.
A Pd-catalyzed direct borylation of various 1,1- and 1,2-disubstituted alkenes
provides trisubstituted alkenyl boronic esters with outstanding yields and
excellent E/Z selectivities via a boryl-Heck pathway. Several
derivatizations of the alkenyl boronic esters allow access to diverse,
stereodefined, functionalized olefins.
W. B. Reid, D. A. Watson, Org. Lett.,
2018, 20, 6822-6826.
A boryl-Heck reaction of terminal alkenes with commercially available
catecholchloroborane (catBCl) as an electrophilic boron reagent provides
trans-alkenyl boronic esters. In situ transesterification allows for rapid
access to various boronic esters, amides, and other alkenyl boron adducts.
W. B. Reid, J. J. Spillane, S. B. Krause, D. A. Watson, J. Am. Chem. Soc., 2016,
138, 5539-5542.
Ni(II) catalyzes a borylation of conjugated alkenyl methyl ethers with B2pin2.
Both E/Z isomers of alkenyl ethers are converted into (E)-alkenyl
boronic esters. This chemoselective method tolerates aryl ether, ester, amide,
and thioether groups.
X. Qiu, Y. Li, L. Zhou, P. Chen, F. Li, Y. Zhang, Y. Ling,
Org. Lett., 2020, 22, 6424-6428.
A palladium-catalyzed oxidative borylation reaction of readily available N-tosylhydrazones
provides di-, tri-, and tetrasubstituted alkenylboronates. This highly efficient
and practical reaction offers mild conditions, broad substrate scope, and good
functional group tolerance. One-pot Suzuki coupling and other transformations
highlight the synthetic utility of the approach.
Y. Ping, R. Wang, Q. Wang, T. Chang, J. Huo, M. Lei, J. Wang, J. Am. Chem. Soc.,
2021, 143, 9769-9780.
An efficient Cu-catalazed borylation of propargylic alcohols provides vinyl-,
allyl-, and (E)-2-boryl allylboronates in very good yield with a broad
substrate scope under mild conditions. Isolation of an allenyl boronate as the
reaction intermediate suggests that an insertion-elimination-type reaction,
followed by borylcupration, is involved.
L. Mao, R. Bertermann, K. Emmert, K. J. Szabo, T. B. Marder, Org. Lett.,
2017, 19, 6586-6589.
In a copper-catalyzed formal carboboration of alkynes, a C-B bond and a C-C bond
are created in a single catalytic cycle. The reaction proceeds with high
regioselectivity and syn-stereoselectivity to form tri- and
tetrasubstituted vinylboronic esters from commercially available
bis(pinacolato)diboron. A subsequent cross-coupling reaction gives access to
highly substituted alkenes.
R. Alfaro, A. Parra, J. Alemán, J. L. G. Ruano, M. Tortosa, J. Am. Chem. Soc., 2012,
134, 15165-15168.
In a copper-catalyzed regio- and stereoselective borylalkylation of
dialkylsubstituted internal alkynes with bis(pinacolato)diboron and alkyl
halides, a borylcopper species containing a novel π-accepting N-heterocyclic
carbene ligand chemoselectively reacted with unactivated internal alkynes over
alkyl halides. The intermediate alkenylcopper species subsequently reacted with
alkyl halides, affording the desired products.
T. Itoh, Y. Shimizu, M. Kanai, J. Am. Chem. Soc., 2016,
138, 7528-7531.
Protoborations of terminal allenes catalyzed by NHC-Cu complexes afford valuable
1,1- or trisubstituted vinylboronates with high site selectivity and
stereoselectivity. The scope of the method, application to natural product
synthesis, and mechanistic details for the observed selectivity are presented.
F. Meng, B. Jung, F. Haeffner, A. H. Hoveyda, Org. Lett., 2013,
15, 1414-1417.
The catalytic property of nanoporous gold for activation of
bis(pinacolato)diboron allows an efficient direct diboration of alkynes in a
heterogeneous process. The nanoporous gold catalyst is able to cleave the B–B
bond of bis(pinacolato)diboron without using any additives.
Q. Chen, J. Zhao, Y. Ishikawa, N. Asao, Y. Yamamoto, T. Jin, Org. Lett., 2013,
15, 5766-5769.
A cobalt-catalyzed method for the diboration of terminal alkynes with B2Pin2
proceeds efficiently at 23°C with excellent 1,1-selectivity and broad functional
group tolerance. With the unsymmetrical diboron reagent PinB-BDan,
stereoselective 1,1-diboration provided products with two boron substituents
that exhibit differential reactivity.
S. Krautwald, M. J. Bezdek, P. J. Chirik, J. Am. Chem. Soc., 2017,
139, 3868-3875.
Rhodium-catalyzed deoxygenations and borylations of ketones with B2pin2
provide alkenes, vinylboronates, and vinyldiboronates. These reactions offer
mild reaction conditions, a broad substrate scope, and excellent
functional-group compatibility. Mechanistic studies support that the ketones
initially undergo a Rh-catalyzed deoxygenation to give alkenes via boron enolate
intermediates.
L. Tao, X. Guo, J. Li, R. Li, Z. Lin, W. Zhao, J. Am. Chem. Soc.,
2020, 142, 18118-18127.
A gem-diborylation of 2-arylvinyl sulfides with bis(pinacolato)diboron
proceeded efficiently with a rhodium catalyst to provide a wide range of
(2,2-diborylvinyl)arenes. Mechanistic studies indicate that the reaction
proceeds from either of the stereoisomers in a stepwise manner via borylative
C-S bond cleavage and subsequent dehydrogenative borylation.
Y. Uetake, M. Isoda, T. Niwa, T. Hosoya,
Org. Lett., 2019, 21, 4933-4938.
In a synthesis of 1,1-diboryl alkenes from terminal alkenes,
1,1-regioselective addition is observed for both conjugated and unconjugated
alkenes. The method provides a wide range of 1,1-diboryl alkenes.
O. O. Idowu, J. C. Hayes, W. B. Reid, D. A. Watson, Org. Lett., 2021, 23,
4838-4842.
Phosphine-free Pd complexes together with alkenyl or aryl iodides were very
efficient catalysts for 1,2-diboration of allenes. This reaction is completely
regioselective and highly stereoselective. Monosubstituted allenes afford
diboration products with mainly Z stereochemistry.
F.-Y. Yang, C.-H. Cheng, J. Am. Chem. Soc., 2001,
123, 761-762.
A convenient and efficient hydroboration of propargyl alcohols was achieved
simply with LiOtBu as the base and (Bpin)2 as the boron
reagent to provide β-Bpin-substituted (E)-allylic alcohols in dimethyl
sulfoxide at room temperature. Both terminal and internal propargyl alcohols
with diverse structures and functional groups underwent the transformation
smoothly.
X. Tian, Y.-K. Zhang, Y.-X. You, J.-R. Han, Q.-S. Cheng, S.-M. Fan, D.-D.
Chen, T.-T. Wang, S. Liu, W. Su, Org. Lett., 2023, 25,
6401-6406.
Substituted alkynoates undergo borylation in a regio-, stereo-, and
chemoselective fashion to afford (Z)-β-boryl-α,β-unsaturated esters in
the presence of bis(pinacolato)diboron and catalytic amounts of both copper(II)
and 4-picoline. The reaction is performed under mild conditions using water as
solvent and open to the atmosphere.
C. L. Peck, J. A. Calderone, W. L. Santos,
Synthesis, 2015, 47, 2242-2248.
A tandem sequence in which Cu/Xantphos catalyzes a B2pin2-syn-hydroboration
of an alkyne whereas Cu/BINAP serves as a photocatalyst for visible
light-mediated isomerization of the resulting alkenyl boronic ester enables a
formal anti-hydroboration of activated internal alkynes.
J. Corpas, M. Gomez-Mendoza, J. Ramírez-Cárdenas, V. A. de la Peña O’Shea, P.
Mauleón, R. G. Arrayás, J. C. Carretero, J. Am. Chem. Soc.,
2022, 144, 13006-13017.
Trialkylphosphines catalyze a regioselective anti-hydroboration of
internal alkynes with pinacolborane reagents to provide (E)-disubstituted
alkenylboronate compounds. The alkenylboronates can be used for derivatizations,
such as protodeborylations, Suzuki-Miyaura couplings, conjugate reductions, and
Diels-Alder reactions.
K. Nagao, A. Yamazaki, H. Ohmiya, M. Sawamura, Org. Lett.,
2018, 20, 1861-1865.
A base-mediated trans-hydroboration of a wide range of propiolamides
provides access to previously elusive primary and secondary (E)-β-borylacrylamides.
The use of n-butyllithium and pinacolborane provides the corresponding
vinylboronates in very good yields with complete regioselectivity and
stereoselectivity.
R. J. Grams, R. G. Fritzemeier, C. Slebodnick, W. L. Santos,
Org. Lett., 2019, 21, 6795-6799.
Addition of an allyl copper species to an isocyanate provides access to
α-vinyl β-boryl amides in high yields and enantioselectivities. The
diversification of these products affords highly useful scaffolds.
S. Byun, A. O. Farah, H. R. Wise, A. Katchmar, P. H.-Y. Cheong, K. A. Scheidt, J. Am. Chem. Soc.,
2022, 144, 22850-22857.
4-Substituted 1,2-oxaborol-2(5H)-ols were prepared through
copper-catalyzed carbomagnesation of propargyl alcohol, followed by the
transmetallation of magnesium to boron in a one-pot procedure. The
Suzuki-Miyaura cross-coupling of these new 2,2-disubstituted alkenylboronic
acids with aryl halides afforded stereodefined 2,3-disubstituted allyl
alcohols in good to excellent yields.
G.-H. Fang, Z.-J. Yan, M.-Z. Deng,
Synthesis, 2006, 1148-1154.
A new method for the synthesis of organoborates starting from α,β-unsaturated
acetals was developed. The available alkoxy-functionalized butadienyl- and
styrylboronic esters cross couple effectively with a broad spectrum of aryl
halides under mild conditions. This method provides an effective
approach to aromatic ketones.
P. B. Tivola, A. Deagostino, C. Prandi, P. Venturello, Org. Lett.,
2002,
4, 1275-1277.
The Cross-coupling reaction of bis(pinacolato)diboron with
β-(trifluoromethanesulfonyloxy)-α,β-unsaturated carbonyl compounds was carried
out in the presence of PdCl2(PPh3)2-2PPh3
(3 mol%) and KOPh in toluene or K2CO3 in dioxane for the
synthesis of cyclic and acyclic β-boryl-α,β-unsaturated esters, amides, and
ketones in high yields.
J. Takagi, A. Kamon, T. Ishiyama, N. Miyaura, Synlett., 2002,
1880-1882.
Monobenzofused 1,4-azaborine phosphine ligands uniquely support Pd-catalyzed
trans-selective hydroboration of terminal and internal 1,3-enynes to furnish
the corresponding dienylboronates in high efficiency and diastereoselectivity.
S. Xu, Y. Zhang, B. Li, S.-Y. Liu, J. Am. Chem. Soc., 2016,
138, 14566-14569.
Alkynylboration of alkynes with alkynyl(pinacol)boranes in the presence of
nickel catalysts gave cis-1-borylbut-1-en-3-yne derivatives. Some
boryl-substituted enynes were reacted with sp2 halides under
Suzuki-Miyaura coupling conditions.
M. Suginome, M. Shirakura, A. Yamamoto, J. Am. Chem. Soc., 2006,
128, 14438-14439.
In the presence of a chiral phosphoramidite ligand, the palladium-catalyzed
diboration of allenes can be executed with high enantioselectivity with a range
of aromatic and aliphatic allenes. A mechanism is proposed based on
isotopic-labeling experiments, stereodifferentiating reactions, kinetic analysis,
and computational experiments.
H. E. Burks, S. Liu, J. P. Morken, J. Am. Chem. Soc., 2007,
129, 8766-8773.
Pd-catalyzed diboration of prochiral allenes occurs exclusively at the
internal position and is accelerated in the presence of Lewis basic ligands.
A chiral ligand was employed, and the enantiomeric excess of a variety of
diboration products was found to be in the range of 86-92% ee.
N. F. Pelz, A. R. Woodward, H. E. Burks, J. D. Sieber, J. P. Morken, J. Am. Chem. Soc.,
2004,
126, 16328-16329.
An efficient Cu-catalazed borylation of propargylic alcohols provides vinyl-,
allyl-, and (E)-2-boryl allylboronates in very good yield with a broad
substrate scope under mild conditions. Isolation of an allenyl boronate as the
reaction intermediate suggests that an insertion-elimination-type reaction,
followed by borylcupration, is involved.
L. Mao, R. Bertermann, K. Emmert, K. J. Szabo, T. B. Marder, Org. Lett.,
2017, 19, 6586-6589.
Bromoboration of propyne with BBr3 proceeds in syn-selectivity
to produce (Z)-2-bromo-1-propenyldibromoborane, which is prone to
stereoisomerization. Treatment with pinacol yields the stable and storable
pinacolboronate. Negishi coupling gives trisubstituted (Z)-alkenylpinacolboronates
in good yields. Iodinolysis of the boronates affords alkenyl iodides in good
yields.
C. Wang, T. Tobrman, Z. Xu, E.-i. Negishi, Org. Lett., 2009,
11, 4092-4095.
A cascade borylation/B-O elimination of propynols and B2pin2
enables an efficient synthesis of tetrasubstituted alkenylboronates in good
yields. Further transformations leading to β-diketones and tetrasubstituted
alkenes demonstrate the synthetic potential of the alkenylboronates as versatile
intermediates in organic synthesis.
Z. Kuang, H. Chen, J. Yan, K. Yang, Y. Lan, Q. Song, Org. Lett.,
2018, 20, 5153-5157.
Commercially available chiral ligands enable a widely applicable, practical,
and scalable strategy for efficient and enantioselective synthesis of
β,γ-unsaturated ketones that contain an α-stereogenic center.
J. del Pozo, S. Zhang, F. Romiti, S. Xu, R. P. Conger, A. H. Hoveyda, J. Am. Chem. Soc.,
2020, 142, 18200-18212.
A Cu/Pd-catalyzed borylallenylation of alkynes with propargylic carbonates
and bis(pinacolato)diboron enables the synthesis of boryl-substituted
ene-allenes. Densely (tetra-, penta-, and hexa-) substituted ene-allenes were
synthesized in acceptable yield with high regio- and stereoselectivity. More
important molecule structures can be obtained by subsequent modifications.
S.-H. Yu, T.-J. Gong, Y. Fu,
Org. Lett., 2020, 22, 2941-2945.
Related
A stereoselective synthesis of tetrasubstituted alkenylboronates, which are
useful synthetic intermediates for further functionalizations, was established
via the lithiation/nucleophilic addition reaction of 1,1-organodiboronates to
carbonyl compounds.
K. Endo, M. Hirokami, T. Shibata, J. Org. Chem., 2010,
75, 3469-3472.
A highly stereoselective boron-Wittig reaction between stable and readily
accessible 1,1-bis(pinacolboronates) and aldehydes furnishes various
synthetically useful di- and trisubstituted vinyl boronate esters.
J. R. Coombs, L. Zhang, J. P. Morken, Org. Lett.,
2015,
17, 1708-1711.
A highly stereoselective boron-Wittig reaction between stable and readily
accessible 1,1-bis(pinacolboronates) and aldehydes furnishes various
synthetically useful di- and trisubstituted vinyl boronate esters.
J. R. Coombs, L. Zhang, J. P. Morken, Org. Lett.,
2015,
17, 1708-1711.
Efficient alkene isomerizations of readily available 1,1-disubstituted
alkenylboronate esters provide synthetically valuable trisubstituted
alkenylboronates. Either stereoisomer of the target alkenylboronate motif can be
obtained by employing different isomerization catalysts.
L. Segura, I. Massad, M. Ogasawara, I. Marek, Org. Lett., 2021, 23,
9194-9198.
A number of alkynyl pinacolboronates were stereoselectively reduced to the
cis-alkenyl pinacolboronates via hydroboration with dicyclohexylborane
followed by chemoselective protodeboronation using acetic acid. Treatment with
potassium hydrogen fluoride smoothly converted these to the corresponding
potassium organotrifluoroborates.
G. A. Molander, N. M. Ellis, J. Org. Chem., 2008,
73, 6841-6844.
A Fe-catalyzed addition of alkyl radicals, formed from the corresponding alkyl
halides, to ethynyl ethynylboronic acid pinacol ester provides Z-vinyl
boronates in high stereoselectivity. The method works best for tertiary and
secondary alkyl iodides.
G. Barzanò, A. Cheseaux, X. Hu, Org. Lett., 2019, 21,
490-493.
A transition-metal-free chemo-, regio-, and stereoselective electrophilic
fluorodesilylation of α-silyl-substituted allylboronate esters with Selectfluor
provides a variety of (E)-boryl-substituted allyl fluorides in good
yields. Further modifications of the obtained (E)-boryl-substituted allyl
fluorides afford allyl or alkyl fluoride derivatives.
Y. Jung, S. H. Cho, Synlett, 2023,
34,
2165-2168.
The cobalt-catalyzed Diels-Alder reaction of alkynyl pinacol boronic esters with various dienes generates cycloadducts in very good regioselectivity. A reaction sequence (Diels-Alder reaction, Suzuki coupling, DDQ oxidation) was successfully performed as a one pot operation without isolation of the intermediates.
G. Hilt, K. I. Smolko, Angew. Chem. Int. Ed., 2003, 42,
2795-2797.
In situ generation of allylic boronates by iridium-catalyzed borylation of
cyclic alkenes in the presence of additives, such as methylimidazole and DBU,
followed a reaction with aldehydes allows the synthesis of stereodefined
homoallylic alcohols. Cycloalkenes without additives as well as acyclic
substrates gave vinylic boronates, which were coupled with organohalides in a
Suzuki-Miyaura sequence.
V. J. Olsson, K. J. Szabó, J. Org. Chem., 2009,
74, 7715-7723.
1-Alkenylboronic acid pinacol esters have been synthesized via a palladium-catalyzed cross-coupling reaction of bis(pinacolato)diboron with 1-alkenyl halides or triflates in toluene at 50°C in the presence of KOPh in high yields with complete retention of configuration of the double bonds. A one-pot synthesis of unsymmetrical 1,3-dienes via the borylation-coupling sequence has been developed.
J. Takagi, K. Takahashi, T. Ishiyama, N. Miyaura, J. Am. Chem. Soc.,
2002,
124, 8001-8006.
The presence of supported gold nanoparticles enables gold-catalyzed silaboration
of terminal alkynes with PhMe2SiBpin. The reaction proceeds at
ambient conditions in very good yields with a regioselectivity opposite to that
observed in the presence of Pd or Pt catalysts. The abnormal regioselectivity is
attributed to steric factors imposed by the Au nanoparticle during the
1,2-addition of silylborane to the alkyne.
C. Gryparis, M. Stratakis, Org. Lett., 2014,
16, 1430-1433.
Pd-catalyzed enantioselective diborations of prochiral allenes followed by allylation reactions with primary imines provide vinyl boronates which may be oxidized to give nonracemic Mannich products. Alternatively, enantiomerically enriched homoallylic amine derivatives may be obtained by protonation and Suzuki cross-coupling of the vinyl boronate.
J. D. Sieber, J. P. Morken, J. Am. Chem. Soc., 2006, 128, 74-75.