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Synthesis of substituted alkenes
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A Pd-catalyzed direct methylation of aryl, heteroaryl, and vinyl boronate esters
with iodomethane occurs with a remarkably broad scope and is suitable for
late-stage derivatization of biologically active compounds.
A. M. Haydl, J. F. Hartwig, Org. Lett., 2019, 21,
1337-1341.
The Zweifel reaction is a powerful transition-metal-free alternative to the
Suzuki-Miyaura reaction for the synthesis of alkenes. This transition-metal-free
coupling process enables the coupling of Grignard reagents or organolithiums for
an enantiospecific synthesis of a wide variety of functionalized acyclic and
cyclic olefin products.
R. J. Armstrong, W. Niwetmarin, V. K. Aggarwal, Org. Lett.,
2017, 19, 2762-2765.
An efficient iron-catalyzed cross-coupling
reaction between organolithium compounds and alkenyl iodides provides the
desired products in good yields and high stereospecificity.
X.-L. Lu, M. Shannon, X.-S. Peng, H. N. C. Wong,
Org. Lett., 2019, 21, 2546-2549.
A selective iron-catalyzed cross-coupling of primary and secondary alkyl
chlorides, bromides, and iodides with alkenylzinc reagents gives the
corresponding olefins in good to excellent yields in a stereospecific manner.
High functional group compatibility is also demonstrated by using combinations
of substrates possessing rather reactive substituents.
T. Niu, W. Zhang, D. Huang, C. Xu, H. Wang, Y. Hu, Org. Lett., 2009,
11, 4474-4477.
N-Methyimidazole as the key additive enables high yielding stereo- and
chemoselective Pd-catalyzed cross-couplings of alkenyl iodides and bromides with
primary and secondary alkyl zinc iodides in THF at room temperature.
A. Krasovskiy, B. H. Lipshutz, Org. Lett., 2011,
13, 3822-3825.
A Ni-catalyzed Suzuki-Miyaura coupling of primary and secondary alkyl halides
including alkyl chlorides with alkenyl-(9-BBN) reagents allows - also in
combination with one pot hydroboration of terminal alkynes - the expedited
synthesis of functionalized alkyl alkenes from readily available alkynes with
complete (E)-selectivity.
T. Di Franco, A. Epenoy, X. Hu, Org. Lett.,
2015,
17, 4910-4913.
Single-electron transmetalation via photoredox/nickel dual catalysis enables
cross-coupling of primary and secondary (bis-catecholato)alkylsilicates with
alkenyl halides via transfer of alkyl radicals under very mild reaction
conditions. The method works with not only alkenyl bromides and iodides but also
previously underexplored alkenyl chlorides.
N. R. Patel, C. B. Kelly, M. Jouffroy, G. A. Molander, Org. Lett., 2016, 18,
764-767.
Nickel catalysis accomplishes a decarboxylative cross-coupling of aliphatic
acid anhydrides with vinyl triflates or halides. This methodology works well
with a broad array of substrates and features abundant functional group
tolerance.
H. Chen, S. Sun, X. Liao,
Org. Lett., 2019, 21, 3625-3630.
The combination of Fe3+/H2O2 mediates a
regioselective alkylation or arylation of alkenes with sulfoxides as alkyl
or aryl reagents. Higher alkenes including di-, tri-, and
tetra-substituted products were regioselectively synthesized. Both aliphatic and
aromatic alkenes could participate in this reaction.
M.-D. Su, Y.-F. Liu, Z.-W. Nie, T.-L. Yang, Z.-Z. Cao, H. Li, W.-P. Luo, Q.
Liu, C.-C. Guo, J. Org. Chem., 2022, 87,
7022-7032.
Xanthate salts are a unique class of visible-light-excitable alkyl radical
precursors that act simultaneously as strong photoreductants and alkyl radical
sources. Upon direct photoexcitation of xanthate anions, efficient deoxygenative
alkenylation and alkylation of a wide range of primary, secondary, and tertiary
alcohols have been achieved avoiding any photocatalysts.
H.-M. Guo, B.-Q. He, X. Wu, Org. Lett.,
2022, 24, 3199-3204.
A palladium-catalyzed Heck reaction proceeds smoothly at room temperature
with a variety of tertiary, secondary, and primary alkyl bromides upon
irradiation with blue light-emitting diodes in the presence of a dual phosphine
ligand system. Probably, a photoexcited-state reactivity of the palladium complex enhances
oxidative addition and suppresses undesired β-hydride elimination.
G.-Z. Wang, R. Shang, W.-M. Cheng, Y. Fu, J. Am. Chem. Soc., 2017,
139, 18307-18312.
A noble-metal-free, photo-induced decarboxylative Heck-type coupling of terminal
alkenes with alkyl carboxylic acids
was achieved in the absence of external oxidants through the synergistic
combination of an organo photo-redox catalyst and a cobaloxime catalyst, with H2
and CO2 as the only byproducts. More than 90 olefins across a wide
range of functionalities were effectively synthesized with this simple protocol.
H. Cao, H. Jiang, H. Feng, J. M. C. Kwan, X. Liu, J. Wu, J. Am. Chem. Soc.,
2018,
140, 16360-16367.
Reactions of (E)-β-nitrostyrenes with triethylborane or
tricyclohexylborane in THF solution at room temperature in the presence of
oxygen in the air as radical initiator generate high yields of trans-alkenes.
(E)-alkenes can also be prepared when (E)-β-nitrostyrenes react
with different radicals, prepared from secondary or tertiary alkyl
iodides in the presence of triethylborane and air.
J.-T. Liu, Y.-J. Jang, Y.-K. Shih, S.-R. Hu, C.-M. Chu, C.-F. Yao, J. Org. Chem., 2001,
66, 6021-6028.
The cooperative action of copper and nickel catalysts enables a stereospecific hydroalkylation
of
terminal alkynes with alkyl iodides to provide E-alkenes with excellent
anti-Markovnikov selectivity. The reaction can be accomplished in the presence of esters, nitriles, aryl bromides,
ethers, alkyl chlorides, anilines, and a wide range of nitrogen-containing
heteroaromatic compounds.
A. Hazra, J. Chen, G. Lalic, J. Am. Chem. Soc.,
2019,
141, 12464-12469.
In a ligand-controlled cobalt-catalyzed regiodivergent alkyne hydroalkylation
of terminal alkynes with alkyl halides, use of bisoxazoline and
pyridine-oxazoline ligands provided (E)-1,2-disubstituted and
1,1-disubstituted alkenes with high E/Z stereoselectivity and
regioisomeric ratio. Internal alkynes provide trisubstituted alkenes. The
methods show excellent functional group compatibility.
Y. Li, D. Liu, L. Wan, J.-Y. Zhang, X. Lu, Y. Fu, J. Am. Chem. Soc.,
2022, 144, 13961-13972.
A silver-catalyzed hydroalkylation
of terminal alkynes with alkylboranes as coupling partners enables an efficient synthesis of
diastereopure Z-alkenes (Z:E > 300:1). This method offers a broad functional group
compatibility. A
1,2-metalate rearrangement of the silver borate intermediate is the key step
responsible for the stereochemical outcome of the reaction.
M. T. Lee, M. G. Goodstein, G. Lalic, J. Am. Chem. Soc.,
2019, 141, 17086-17091.
A method to produce 1,2-disubstituted olefins in high Z selectivity via
reductive cross-coupling of alkyl halides with terminal arylalkynes employs
inexpensive and nontoxic catalyst (iron(II) bromide) and reductant (zinc). The
substrate scope encompasses primary, secondary, and tertiary alkyl halides, and
the reaction tolerates a large number of functional groups.
C. W. Cheung, F. E. Zhurkin, X. Hu, J. Am. Chem. Soc., 2015,
137, 4932-4935.
The stereochemical outcome of Negishi coulings of Z-alkenyl halides is
highly ligand dependent. A modified method solves the stereochemical issue and
significantly improves yields of Negishi couplings in general even at ambient
temperature.
A. Krasovskiy, B. H. Lipshutz, Org. Lett., 2011,
13, 3818-3821.
Stereoretentive Pd-Catalyzed Kumada-Corriu Couplings of Alkenyl Halides at
Room Temperature
A. L. Krasovskiy, S. Haley, K. Voigtritter, B. H. Lipshutz, Org. Lett.,
2014,
16, 4066-4069.
Sarcosine is an excellent ligand for cobalt-catalyzed carbon-carbon
cross-coupling of Grignard reagents with allylic and vinylic bromides. The
system performs efficiently when phenyl and benzyl Grignards are coupled with
alkenyl bromides. Notably, previously unachievable Co-catalyzed coupling of
allylic bromides with Grignards to linearly coupled α-products was also realized.
R. Frlan, M. Sova, S. Gobec, G. Stavber, Z. Časar, J. Org. Chem.,
2015,
80, 7803-7809.
A nonionic amphiphile (PTS) enables a simple approach to Pd-catalyzed stereoselective sp3-sp2
cross-couplings between alkyl and alkenyl bromides in the presence of zinc
powder in water to give coupled products in good yields without prior formation
of the organozinc reagents. The reaction is conducted at room temperature and
tolerates various functional groups.
A. Krasovskiy, C. Duplais, B. H. Lipshutz, Org. Lett., 2010,
12, 4742-4744.
An alkenylation of alkyl electrophiles using nearly stoichiometric amounts of
air- and moisture-stable potassium organotrifluoroborates tolerates various
functional groups on both the nucleophilic and electrophilic partner. Reactions
of highly substituted E- and Z-alkenyltrifluoroborates, as well as
vinyl- and propenyltrifluoroborates, were successful with retention of
stereochemistry and regiochemistry.
G. A. Molander, O. A. Argintaru, Org. Lett., 2014,
16, 1904-1907.
A multicatalytic isomerization/cross-coupling sequence enables a
stereoselective coupling of readily available alkenyl methyl ethers with various
Grignard reagents to provide highly substituted alkenes. A cationic iridium
catalyst for the stereoselective isomerization of allyl methyl ethers to methyl
vinyl ethers is compatible with a nickel catalyst for the subsequent
cross-coupling.
C. Romano, C. Mazet, J. Am. Chem. Soc.,
2018,
140, 4743-4750.
An UV light-induced, copper-catalyzed decarboxylative coupling of
α,β-unsaturated acids with 1°, 2°, and 3° alkyl iodides provides alkenes in good
yields and high stereoselectivities.
C. Wang, Y. Lei, M. Guo, Q. Shang, H. Liu, Z. Xu, R. Wang, Org. Lett.,
2017, 19, 6412-6415.
The combination of Pd(PPh3)2Cl2 with Xantphos
efficiently catalyzes a decarboxylative Heck reaction of vinyl arenes and vinyl
heteroarenes with aliphatic N-(acyloxy)phthalimides under irradiation of
blue LEDs at room temperature. A broad scope of secondary, tertiary, and
quaternary carboxylates, including α-amino acid derived esters, can be converted
with high stereoselectivity.
G.-Z. Wang, R. Shang, Y. Fu, Org. Lett.,
2018, 20, 888-891.
The presence of FeCl3/CuTC enables an efficient coupling of
functionalized aryl Grignard reagents and 1-arylvinyl halides to access
1,1-diarylethylenes of biological interest. This bimetallic system proved to be
superior to the use of Fe or Cu catalyst alone. The synthetic utility of this
protocol is illustrated in the field of steroid chemistry.
A. Hamze, J.-D. Brion, M. Alami, Org. Lett., 2012,
14, 2782-2785.
The use of 2% Pd2(dba)3/8% PCyp3/NMI in
THF/NMP at 80°C achieves the cross-coupling of a range of
β-hydrogen-containing primary alkyl iodides, bromides, chlorides, and
tosylates with an array of alkyl-, alkenyl-, and arylzinc halides. This
method tolerates various functional groups.
J. Zhou, G. C. Fu, J. Am. Chem. Soc.,
2003,
125, 12527-12530.
An insoluble, amphiphilic and polymeric palladium catalyst (PdAS) is an excellent catalyst for the
Suzuki-Miyaura reaction. The catalyst is reusable after easy work up and showed
good stability in any reaction medium.
Y. M. A. Yamada, K. Takeda, H. Takashashi, S. Ikegami, J. Org. Chem.,
2003,
68, 7733-7741.
"Ligandless" palladium complexes can catalyze the zirconium-Negishi
reactions of alkyl electrophiles. Ligandless processes offer low cost,
simplicity, and ease of purification.
S. L. Wiskur, A. Korte, G. C. Fu, J. Am. Chem. Soc.,
2004,
126, 82-83.
A combination of nickel(II) acetylacetonate and (Z)-3,3-dimethyl-1,2-bis(diphenylphosphino)but-1-ene
catalyzes cross-coupling reactions of alkyl aryl sulfides and alkenyl alkyl
sulfides with primary and secondary alkyl Grignard reagents.
S. Kanemura, A. Kondoh, H. Yorimitsu, K. Oshima, Synthesis, 2008,
2659-2660.
A copper-catalyzed hydroalkylation of terminal alkynes using alkyl triflates
as coupling partners and (Me2HSi)2O as a hydride donor
proceeds with excellent anti-Markovnikov regioselectivity and provides
exclusively (E)-alkenes. Both alkyl- and aryl-substituted alkynes can be
used as substrates, together with 1° alkyl and benzylic triflates. Finally, the
transformation can be accomplished in the presence of a wide range of functional
groups.
M. R. Uehling, A. M. Suess, G. Lalic, J. Am. Chem. Soc., 2015,
137, 1424-1427.
In the presence of Co(PPh3)2I2, PPh3,
water, and zinc powder, the reductive coupling of alkynes with alkenes
having an electron-withdrawing substituent proceeded smoothly in
acetonitrile to give the corresponding reductive coupling products in fair
to excellent yields. Possible mechanisms for this highly regio- and
stereoselective ene-yne reaction are proposed.
C.-C. Wang, P.-S. Lin, C.-H. Cheng, J. Am. Chem. Soc., 2002,
124, 9696-9697.
An efficient Fe-catalyzed cross-electrophile coupling of
vinyl halides with tertiary alkyl methyl oxalates provides vinylated carbon quaternary centers
with
excellent functional group tolerance and broad substrate scope. A
cascade radical cyclization and vinylation affords complex bicyclic and spiral
structural motifs.
Y. Ye, H. Chen, K. Yao, H. Gong,
Org. Lett., 2020, 22, 2070-2075.
Use of a zirconocene catalyst based on the Brintzinger ligand and catalytic
amounts of methyl aluminoxanes (MAO) effect a >99% regiocontrol of Negishi
carboaluminations of 1-alkynes in toluene.
B. H. Lipshutz, T. Butler, A. Lower, J. Am. Chem. Soc., 2006,
128, 15396-15398.
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.
The use of the Xantphos ligand in a mild palladium-catalyzed Kumada-Corriu
reaction of secondary benzylic bromides with aryl and alkenyl Grignard reagents
minimizes the undesired β-elimination pathway. The corresponding cross-coupling
products can be isolated in good yields with inversion of the configuration.
A. López-Pérez, J. Adrio, J. C. Carretero, Org. Lett., 2009,
11, 5514-5517.
A Ni-catalyzed asymmetric reductive cross-coupling between vinyl bromides and
benzyl chlorides provides direct access to enantioenriched products bearing
aryl-substituted tertiary allylic stereogenic centers from simple, stable
starting materials. A broad substrate scope can be converted under mild reaction
conditions without pregeneration of organometallic reagents and the
regioselectivity issues commonly associated with allylic arylation.
A. H. Cherney, S. E. Reisman,
J. Am. Chem. Soc., 2014,
136, 14365-14366.
An enantioselective Ni-catalyzed cross-coupling of N-hydroxyphthalimide
esters with vinyl bromides proceeds under mild conditions and uses tetrakis(N,N-dimethylamino)ethylene
as a terminal organic reductant. Good functional group tolerance is demonstrated,
with over 20 examples of reactions that proceed with excellent
enantioselectivity.
N. Suzuki, J. L. Hofstra, K. E. Poremba, S. E. Reisman, Org. Lett.,
2017, 19, 2150-2153.
The air-stable nickel(II) complex trans-(PCy2Ph)2Ni(o-tolyl)Cl
enables an internally selective Mizoroki-Heck-type coupling of substituted
benzyl chlorides with terminal alkenes at room temperature. This operationally
simple and highly regioselective reaction provides rapid, convergent access to
substituted allylbenzene derivatives in high yield and can be carried out on the
benchtop with no purification or degassing of solvents or reagents.
E. A. Standley, T. F. Jamison, J. Am. Chem. Soc., 2013,
135, 1585-1592.
Nickel-catalyzed intermolecular benzylation and heterobenzylation of unactivated
alkenes with benzyl chlorides provides functionalized allylbenzene derivatives.
In contrast to analogous palladium-catalyzed processes, all reactions described
herein employ electronically unbiased aliphatic olefins (including ethylene),
proceed at room temperature, and provide 1,1-disubstituted olefins with very
high selectivity.
R. Matsubara, A. C. Gutierrez, T. F. Jamison, J. Am. Chem. Soc., 2011,
133, 19020-19023.
The palladium-catalyzed reaction of allyl acetates with aryl- and
vinyltin reagents gave good yields of cross-coupled products. The reaction
was mild and tolerant of functionality (-CO2R, -OH, -OSiR3,
-OMe) in the tin reagent. Inversion of stereochemistry at the acetate center
was observed, with retention of the geometry of the olefin of the allyl
group and with exclusive coupling at the primary position. Retention of
geometry of the olefin in the vinyltin reagents was also observed.
L. Del Valle, J. K. Stille, L. S. Hegedus, J. Org. Chem, 1990,
55, 3019-3023.
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.
C-O bond cleavage of lithium alkoxides occurs readily at room temperature in the
presence of titanium(IV) halides. Capture of the resultant carbocation by
alkynes provides an efficient route to trisubstituted (E)-alkenyl halides
with high stereoselectivity.
M.-L. Yao, T. R. Quick, Z. Wu, M. P. Quinn, G. W. Kabalka, Org. Lett., 2009,
11, 2647-2649.
A robust copper-catalyzed or transition-metal-free alkylation of gem-difluoroalkenes
with alkyl Grignard reagents proceeded very smoothly in the presence of 25 mol %
of CuCN or under transition-metal-free conditions. Especially tertiary and
secondary alkyl-substituted fluoroalkenes can be isolated in good to excellent
yields with excellent Z stereoselectivity.
W. Dai, H. Shi, X. Zhao, S. Cao, Org. Lett.,
2016, 18, 4284-4287.
A catalyst-induced defluorinative, alkylation or metal-free hydroalkylation
of gem-difluoroalkenes provides a mild and practical approach to
important and monofluoroalkenes and difluoromethylene-containing compounds
under visible light irradiation with good yields.
F. Liu, Z. Zhuang, Q. Qian, X. Zhang, C. Yang, J. Org. Chem., 2022, 87,
2730-2739.
A mild and efficient zinc-mediated decarboxylative alkylation of gem-difluoroalkenes
with N-hydroxyphthalimide (NHP) esters provides Z-monofluoroalkenes
in good yields. The reaction tolerates a broad range of functional groups and
can be easily scaled up.
L. Yu, M.-L. Tang, C.-M. Si, Z. Meng, Y. Liang, J. Han, X. Sun, Org. Lett.,
2018, 20, 4579-4583.
The visible light mediated coupling of α-fluoroacrylic acids with N-hydroxyphthalimide
(NHPI) redox-active esters provides monofluoroalkenes under mild conditions.
This decarboxylative reaction exhibited excellent functional group
compatibility and delivered monofluoroalkene products with excellent Z-stereoselectivity.
X. Bai, L. Huang, P. Zhou, H. Xi, J. Hu, Z. Zuo, H. Feng, J. Org. Chem., 2022, 87,
4998-5004.
A visible-light-induced perfluoroalkylation reaction of aryl acrylic acids
uses perfluoroalkyl iodides as radical precursors and inexpensive eosin Y as a
photocatalyst. The easy accessibility of perfluoroalkyl iodides and the broad
substrate scope, mild conditions, and metal-free catalyst make this
decarboxylative protocol applicable for the transformation of inexpensive raw
materials to high-value chemicals.
M. Yu, K. Niu, Z. Wang, Y. Liu, Q. Wang, Org. Lett.,
2022, 24, 7622-7626.
A nickel-catalyzed hydrotrifluoroalkylation of terminal alkynes provides
allylic trifluoromethyl terminal alkenes with high efficiency, broad substrate
scope, and favorable functional group compatibility. The combination of nitrogen
and phosphine ligands, especially electron-rich ones, plays an indispensable
role in the course of the reaction.
T. Zhang, Y.-W. Zuo, R.-X. Jin, Y.-F. Zhang, B.-B. Wu, X.-S. Wang, Org. Lett., 2023, 25,
3578-3584.
An easy access to (Z)-trisubstituted allylic alcohols is based on
E to Z isomerization of 1-bromo-1-dialkylvinylboranes upon
reaction with dialkylzinc reagents. Subsequent transmetalation to give (Z)-trisubstituted
vinylzinc species is followed by trapping with aldehydes to furnish a series
of (Z)-trisubstituted allylic alcohols.
Y. K. Chen, P. J. Walsh, J. Am. Chem. Soc.,
2004,
126, 3702-3703.
An efficient Fe(III)-catalyzed direct coupling of alkenes with alcohols and
cross-coupling of alcohols with alcohols gives the corresponding substituted (E)-alkenes
stereospecifically. Mild conditions, atom efficiency, environmental soundness,
and stereospecificity are features that make this procedure very attractive.
Additionally, this reaction could be scaled up.
Z.-Q. Liu, Y. Zhang, L. Zhao, Z. Li, J. Wang, H. Li, L.-M. Wu, Org. Lett., 2011,
13, 2208-2211.
An efficient Cu(OTf)2-catalyzed sp3-sp2
coupling of propargylic alcohols with terminal alkenes gives a diverse range of
1,4-enynes in very good yields. The reaction is tolerant to air and
atom-economical.
G.-B. Huang, X. Wang, Y.-M. Pan, H.-S. Wang, G.-Y. Yao, Y. Zhang, J. Org. Chem., 2013,
78, 2742-2745.
The use of bisphosphine ligands with a large P-Pd-P bite angle allowed to
synthesize Z-chlorinated internal alkenes in good yields by a selective
Suzuki-Miyaura monocoupling process of 9-alkyl-9-BBN with
1,1-dichloro-1-alkenes. These monochlorinated olefins could be further
transformed providing stereospecifically trisubstituted olefins.
F. Liron, C. Fosse, A. Pernolet, E. Roulland, J. Org. Chem., 2007,
72, 2220-2223.
An additive-free, clean conjugate addition reaction of organosiloxanes to α,β-unsaturated
compounds is catalyzed by a cationic rhodium complex in dioxane/water. The
mechanism involves a transmetalation step between the rhodium complex and the
silicon reagent.
S. Oi, Y. Honma, Y. Inoue, Org. Lett., 2002,
4, 667-669.
C2-symmetric chiral diene ligands based on a 3,7-disubstituted
bicyclo[3.3.1]nona-2,6-diene readily bind to rhodium(I). These rhodium complexes
act as effective catalysts for 1,4-addition of alkenyl- and arylboronic acids to
various α,β-unsaturated ketones, including several combinations that were
previously difficult to provide high enantioselectivity.
R. Shintani, Y. Ichikawa, K. Takatsu, F.-X. Chen, T. Hayashi, J. Org. Chem., 2009,
74, 869-873.
A (thio)urea cocatalyst accelerates O-monoacyltartaric acid (MAT)-catalyzed
enantioselective conjugate additions of boronic acid to unsaturated ketone.
T. Yoshimitsu, Y. Kuboyama, S. Nishiguchi, M. Nakajima, M. Sugiura,
Org. Lett., 2020, 22, 3780-3784.
NHC/palladium cooperative catalysis enables a highly stereoselective umpolung
1,4-addition of vinyl bromides to enals to provide various valuable
γ,δ-unsaturated carbonyl derivatives in excellent yields. The NHC acts as both
organocatalyst and ligand for palladium.
B. Ling, W. Yang, Y.-E. Wang, J. Mao, Org. Lett., 2020, 22,
9603-9608.
A Pd-catalyzed three-component reaction of 3-(pinacolatoboryl)allyl acetates,
aldehydes, and organoboranes provides (Z)-anti-homoallylic
alcohols with high levels of diastereoselectivity and alkene stereocontrol.
Y. Horino, A. Aimono, H. Abe, Org. Lett.,
2015,
17, 2824-2827.
Conjugate addition of dimethyl alkenylboronates to α,β-unsaturated ketones in the presence of catalytic amounts of 3,3'-disubstituted binaphthols provides alkenylation products in good yields and
high enantioselectivities.
T. R. Wu, J. M. Chong, J. Am. Chem. Soc., 2007,
129, 4908-4909.
A direct conjugate addition of simple alkenes to enones has been achieved in
the presence of a Ni(0)/PCy3 catalyst. This reaction is a
straightforward method for the introduction of an alkenyl group at the
β-position of enones.
S. Ogoshi, T. Haba, M. Ohashi, J. Am. Chem. Soc., 2009,
131, 10350-10351.
Cobalt complex/Zn systems effectively catalyze the reductive coupling of
activated alkenes with alkynes in the presence of water to give substituted
alkenes with very high regio- and stereoselectivity in excellent yields.
H.-T. Chang, T. T. Jayanth, C.-C. Wang, C.-H. Cheng, J. Am. Chem. Soc.,
2007,
129, 12032-12041.
An efficient highly regio- and stereoselective iron-catalyzed conjugate addition
of 2,3-allenoates with primary or secondary alkyl, phenyl, or vinyl Grignard
reagents gives multi-substituted β,γ-unsaturated enoates in good yields. The in
situ formed magnesium dienolate may readily react with different electrophilic
reagents to construct an allylic quaternary carbon at the α-position of the
ester group.
Z. Lu, G. Chai, S. Ma, J. Am. Chem. Soc., 2007,
129, 14546-14547.
A copper-catalyzed highly anti-selective radical 1,2-alkylarylation of
terminal alkynes with aryl boronic acids and alkyl bromides providesg facile
access to various stereodefined trisubstituted alkenes in high yield under mild
reaction conditions. The reaction exhibits high compatibility with a wide range
of terminal alkynes and diverse aryl boronic acids.
J.-B. Tang, J.-Q. Bian, Y.-S. Zhang, Y.-F. Cheng, H.-T. Wen, Z.-L. Yu, Z.-L.
Yu, Z.-L. Li, Q.-S. Gu, G.-Q. Chen, X.-Y. Liu, Org. Lett.,
2022, 24, 2536-2540.
Reductive coupling of enones or enals with alkynes using reducing agents such
as organozincs, organoboranes, organosilanes, and methanol is cost-effective,
and tolerant of many functional groups. Isotopic labeling strategies have
provided supporting evidence for the mechanistic proposals.
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A nickel-catalyzed intermolecular reductive coupling of enones and alkynes
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organometallic, and a variety of functional groups including free hydroxyls and
esters are tolerated.
A. Herath, B. B. Thompson, J. Montgomery, J. Am. Chem. Soc., 2007,
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A three-component nickel-catalyzed coupling of enals, alkynes, and silanes forms
an enol silane and a trisubstituted alkene with >98:2 stereoselectivity. The
reaction tolerates a broad range of functionality including aldehydes, ketones,
esters, free hydroxyls, and basic secondary amines.
A. Herath, J. Montgomery, J. Am. Chem. Soc., 2008,
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A conjugate addition of organosiloxanes to α,β-unsaturated carbonyl
compounds catalyzed by a cationic rhodium complex generated from [Rh(cod)(MeCN)2]BF4
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enantioselectivities.
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of 1,3-bis(diphenylphosphino)propane and CsF in dioxane at 60°C under carbon
dioxide atmosphere gave carboxylic acids in good yields.
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A Zr-catalyzed carboalumination of terminal alkynes followed by in situ
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excellent regioselectivity and perfect stereoselectivity.
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asymmetric cross-coupling with bromoalkenes to generate allyl boronates with
high levels of enantioselectivity. Oxidation of these allyl boronates with
hydrogen peroxide provides secondary allylic alcohols, whereas nitrosobenzene as
oxidant furnishes nonracemic tertiary allylic alcohols.
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A copper(I)-catalyzed regio- and stereoselective three-component coupling
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boronates. A subsequent allylboration of
aldehydes diastereoselectively furnished the corresponding homoallylic alcohols
that bear a quaternary carbon.
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A palladium-catalyzed double
coupling of nitromethane with vinyl triflates and bromide generates homo allyl nitro products via a
tandem cross-coupling/π-allylation sequence. The resultant process exploits the anion stabilizing and leaving group
properties of nitromethane and provides a
mild and convenient entry to nitroethylated products, which are versatile
precursors to β,γ-unsaturated carbonyls, homoallylic amines, and nitrile oxides.
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The combination of nickel and ruthenium complexes catalyzes a photoinduced
decarboxylative cross-coupling between α,β-unsaturated carboxylic acids and
cycloketone oxime esters. The reaction efficiently provides various cyanoalkyl
alkenes under mild reaction conditions.
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A highly regio- and stereoselective coupling of (Z)-1,2-bis(aryl(alkyl)thio)alkenes
and Grignard reagents in the presence of a Ni catalyst under mild conditions
enables an efficient route for the synthesis of (Z)-vinylic sulfides. (Z)-vinylic
sulfides are important intermediates in the synthesis of tri- and
tetrasubstituted alkenes.
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The reaction of 1-alkynyl sulfides and alkynyl sulfoxides with Et3Al
in the presence of Cp2ZrCl2 as catalyst provides
trisubstituted 1-alkenyl sulfides in good yields with high regio- and
stereoselectivity. Depending on the equivalents of Et3Al, 1-alkynyl
sulfoxides can also be reduced to 1-alkynyl sulfides.
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An efficient iron-catalyzed cross-coupling of primary alkyl Grignard reagents
allows the use of alkenyl and aryl pivalates as electrophiles under mild
conditions. The combination of an inexpensive and stable carboxylate
electrophile and an iron catalyst would generate ample advantages.
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On exposure to BuLi, 3-bromo-2-iodocyclopent-2-enol O-TBS ether
undergoes iodine-lithium permutation with complete regioselectivity.
Reaction with different electrophiles affords the corresponding
2-substituted-3-bromocyclopentenol derivatives. Subsequent bromo-lithium
exchange with t-BuLi, followed by reaction with an equal or different
electrophile, affords 2,3-disubstituted cyclopentenols.
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Opening of the epoxide ring of enantiopure (2R,1'S)-2-(1-aminoalkyl)epoxides
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selectivity and in high yields.
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A gem-difluoroolefination of trifluoroacetaldehyde N-triftosylhydrazone
with organoboronic acids - including alkylboronic acids - is operationally
simple, free of transition metals, and suitable for a broad range of substrates.
Moreover, the utility of the products was demonstrated by further conversion of
the gem-difluorovinyl group.
Y. Ma, B. R. P. Reddy, X. Bi,
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A diastereoselective Pd(0)-catalyzed Hiyama cross-coupling reaction of gem-difluoroalkenes
provides fluoroalkenes in good yields. The use of organosilicon reagents in this
reaction is advantageous over other organometallic reagents by allowing the
introduction of a wide range of functional groups, including challenging alkyl
groups.
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A convenient Fe-catalyzed A-D-A-T-type radical-dual-difunctionalization and
cross-coupling of two different alkenes provides chain elongated and
trifluoromethylated aromatic alkenes.
J. Zhao, R.-X. Liu, C.-P. Luo, L. Yang,
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A nickel-catalyzed alkylation/arylation of 1-chloro-3,3,3-trifluoroprop-1-ene
(HCFO-1233zd) with alkyl/aryl zinc reagents and a cobalt-catalyzed reductive
cross-coupling between HCFO-1233zd and aryl bromides provide
1-(trifluoromethyl)alkenes. These approaches feature broad substrate scope, high
functional group tolerance, and the use of industrial feedstocks and low-cost Ni
or Co catalysts.
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A cobalt-catalyzed photochemical synthesis of allylic trifluoromethanes from
styrene derivatives using 2,2,2-trifluoroethyl iodide complements existing
approaches, providing an alternative bond construction strategy to access these
compounds. The process may be conducted in continuous mode in a photochemical
flow reactor.
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A simple and efficient 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU)-promoted
Heck-type alkene perfluoroalkylation of alkenes with perfluoroalkyl iodides in
good yields proceeds smoothly via a radical process under visible light
irradiation in the absence of an additional photocatalyst in ethyl acetate as a
green solvent. DBU acts as both a halogen bond acceptor and a base.
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An operationally simple Pd-catalyzed three component reaction involving terminal
alkynes, boronic acids, and perfluoroalkyl iodides gives trisubstituted
perfluoroalkenes in a highly regio- and stereocontrolled manner by simultaneous
additions across the triple bond in a radical-mediated process. The reaction is
broad in scope and tolerates many functional groups.
Z. Li, A. García-Domínguez, C. Nevado, J. Am. Chem. Soc., 2015,
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