Categories: C-C Bond Formation > Chains >
Allylic Substitutions, Allylation
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Recent Literature
Nickel-Catalyzed Asymmetric Negishi Cross-Couplings of Secondary Allylic
Chlorides with Alkylzincs
S. Son, G. C. Fu, J. Am. Chem. Soc., 2008,
130, 2756-2757.
The reaction of secondary and tertiary alkyl halides with benzylic or allylic
Grignard reagents in the presence of a catalytic amount of silver nitrate in
ether yielded the corresponding cross-coupling products in high yields. The
coupling reaction provides efficient access to quaternary carbon centers.
H. Someya, H. Ohmiya, H. Yorimitsu, K. Oshima, Org. Lett., 2008,
10, 969-971.
Boron "ate" complexes derived from pinacol boronic esters and tert-butyl
lithium undergo stereospecific transmetalation to copper cyanide, followed by
coupling with alkynyl bromides, allyl halides, propargylic halides, β-haloenones,
hydroxylamine esters, and acyl chlorides. This simple transformation converts
primary and secondary alkylboronic esters to a wide array of useful compounds.
N. Xu, H. Liang, J. P. Morken, J. Am. Chem. Soc.,
2022, 144, 11546-11552.
The use of Ni(dppe)Cl2 as catalyst resulted in the cross-coupling of
allylic alcohols with primary alkyl Grignard reagents and cyclopropylmagnesium
bromide, whereas Ni(PCy3)2Cl2 and dcype led to
the reduction of allylic alcohols in the presence of alkyl Grignard reagents.
Secondary alkyl Grignard reagents except cyclopropylmagnesium bromide always led
to reduction of allylic alcohols.
B. Yang, Z.-X. Wang, J. Org. Chem., 2020, 85,
4772-4784.
Electrochemistry enables smooth Zn-mediated allylic alkylations in aqueous media
under air in the presence of a Pd catalyst between a full range of alkyl halides
(primary, secondary, and tertiary) and substituted allylic halides.
Y.-L. Lai, J.-M. Huang, Org. Lett.,
2017, 19, 2022-2025.
Photoredox/nickel dual catalysis enables a radical-mediated functionalization
of allyl alcohol (derivatives) with a variety of alkyl 1,4-dihydropyridines with
high linear and E-selectivity. This reaction avoids harsh conditions (e.g.,
strong base, elevated temperature). Additionally, using aryl sulfinate salts as
radical precursors, allyl sulfones can also be obtained.
Z.-J. Wang, S. Zheng, E. Romero, J. K. Matsui, G. A. Molander,
Org. Lett., 2019, 21, 6543-6547.
Efficient enantioselective Cu-catalyzed alkylations of aromatic and
aliphatic allylic phosphates bearing di- and trisubstituted olefins are
promoted in the presence of a readily available chiral amino acid-based
ligand. Tertiary and quaternary stereogenic carbon centers are delivered
regioselectively in high ee.
M. A. Kacprzynski, A. H. Hoveyda, J. Am. Chem. Soc.,
2004,
126, 10676-10681.
TiCl4 efficiently promotes the replacement of hydroxyl groups in
tertiary, benzylic, and allylic alcohols, and even nonactivated secondary
alcohols, by an allyl group in high yields. The reaction usually proceeds within
minutes at room temperature.
A. Hassner, C. R. Bandi, Synlett, 2013, 24,
1275-1279.
Direct Csp3−Csp3 coupling of various aliphatic
trimethylsilyl ethers and allylsilanes is effectively catalyzed by InCl3
and I2. The transformation probably involves an in situ-derived
combined Lewis acid of InCl3 and Me3SiI. The reaction
allows the construction of quaternary-quaternary and quaternary-tertiary
carbon-carbon bonds and tolerates aryl halide moieties.
T. Saito, Y. Nishimoto, M. Yasuda, A. Baba, J. Org. Chem., 2007,
72, 8588-8590.
A Cu-catalyzed cross-coupling reaction of allyl boron ester with halogenated
alkanes provides a mild and efficient method for the construction of saturated
C(sp3)-C(sp3) bonds. This protocol works with nonactivated
primary, secondary, and even tertiary halogenated alkanes under mild conditions.
G.-Z. Wang, J. Jiang, X.-S. Bu, J.-J. Dai, J. Xu, Y. Fu, H.-J. Xu, Org. Lett.,
2015,
17, 3682-3685.
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 promising new approach to a generalized allylation process uses various
easily accessible allyl diphenylphosphine oxides as radical trapping agents
for the allylation of ditihocarbonates.
G. Ouvry, B. Quiclet-Sire, S. Z. Zard, Angew. Chem. Int. Ed., 2006,
45, 5002-5006.
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.
A Pd(0)-catalyzed allylic cross-coupling of homoallylic tosylate substrates
with boronic acids and pinacol esters uses 2-(4,5-dihydro-2-oxazolyl)quinoline
(quinox) as a ligand and is performed at ambient temperature. The scope of the
reaction is broad in terms of both the boronate and the tosylate, that includes
secondary tosylates.
B. J. Stokes, S. M. Opra, M. S. Sigman, J. Am. Chem. Soc., 2012,
134, 11408-11411.
B(C6F5)3 catalyzes a highly effective
allylation of secondary benzylic alcohol derivatives with allylsilanes. The
reaction tolerates a broad range of additional functionalities, such as bromo,
acetoxy, and primary benzyloxy groups.
M. Rubin, V. Gevorgyan,
Org. Lett., 2001, 3, 2705-2707.
In a Pd-catalyzed cross-coupling of aromatic and aliphatic allylic carbonates
and allylB(pin), small-bite-angle ligands favor the branched substitution
product. This mode of regioselection is consistent with a reaction that operates
by a 3,3′ reductive elimination reaction. In the presence of appropriate chiral
ligands, this reaction is rendered enantioselective.
P. Zhang, L. A. Brozek, J. P. Morken, J. Am. Chem. Soc., 2010,
132, 10686-10688.
Carreira's iridium-(P, olefin) phosphoramidite-based catalytic system enables
an asymmetric allyl-allylboronate cross-coupling with high
enantioselectivity. This transformation tolerates a large variety of
racemic branched allylic alcohols and allylboronate substrates. The utility of
the coupling is demonstrated in a concise catalytic asymmetric synthesis of (-)-preclamol.
Y. Zheng, B.-B. Yue, K. Wei, Y.-R. Yang, Org. Lett.,
2018, 20, 8035-8038.
Optimized reaction conditions expand the scope of Pd-catalyzed allyl-allyl
couplings to allow the generation of 1,5-dienes with tertiary centers adjacent
to quaternary centers as well as a unique set of cyclic structures. Using a
chiral bidentate diphosphine ligand, the asymmetric cross-coupling of allylboron
reagents and allylic electrophiles establishes 1,5-dienes with adjacent
stereocenters in high regio- and stereoselectivity.
M. J. Ardolino, J. P. Morken, J. Am. Chem. Soc., 2014,
136, 7092-7100.
A palladium-catalyzed cross-coupling of allyl boronates and chiral propargyl
acetates
delivers chiral 1,5-enynes with excellent levels of chirality transfer. The
reaction can be applied across a broad range of substrates.
M. J. Ardolino, J. P. Morken, J. Am. Chem. Soc., 2012,
134, 8770-8773.
A highly enantioselective Sonogashira type synergistic Rh and Cu catalysis of
readily available terminal alkynes and racemic allylic carbonates provides
branched 1,4-enynes under neutral conditions. Aliphatic and aromatic terminal
alkynes with various functional groups could be used directly.
W.-Y. Huang, C.-H. Lu, S. Ghorai, B. Li, C. Li, J. Am. Chem. Soc.,
2020, 142, 15276-15281.
A direct dehydrative coupling of terminal alkynes with allylic alcohols is
catalyzed by Pd(PPh3)4 in the presence of an N,P-ligand
and Ti(OiPr)4. The coupling reaction tolerates various
functional groups and provides a valuable synthetic tool to access 1,4-enynes.
Y.-X. Li, Q.-Q. Xuan, L. Liu, D. Wang, Y.-J. Chen, C.-J. Li, J. Am. Chem. Soc., 2013,
135, 12536-12539.
An iridium-catalyzed stereoselective coupling of allylic ethers and alkynes
provides 3,4-substituted 1,5-enynes with excellent regio-, diastereo-, and
enantioselectivities, and the protocol is functional group tolerant. Moreover,
conditions are reported that allow the reaction to proceed with complete
reversal of diastereoselectivity.
J. Zhu, Y. Wang, A. D. Charlack, Y.-M. Wang, J. Am. Chem. Soc.,
2022, 144, 15480-15487.
A neighboring boronate group in vicinal bis(boronic esters) provides a
dramatic rate acceleration in transmetalation to copper and thereby enables
unprecedented site-selective cross-couplings allyl, alkynyl, and propargyl
electrophiles as well as a simple proton. This cross-coupling operates under
practical experimental conditions.
N. Xu, Z. Kong, J. Z. Wang, G. J. Lovinger, J. P. Morken, J. Am. Chem. Soc.,
2022, 144, 17815-17823.
Metalation of 3-methyl-3-buten-1-ol with n-BuLi in the presence of TMEDA
followed by treatment of the resulting dianion with alkyl halides is a general
route to 3-methylene-1-alkanols. This chemistry could be used advantageously for
the preparation of butyrolactone, pyranol, stinkbug pheromone, topostin, and
γ-geraniol precursors.
K. H. Yong, J. A. Lotoski, J. M. Chong, J. Org. Chem., 2001,
66, 8248-8251.
An efficient Ni-catalyzed reductive carboxylation of brached and linear allylic
alcohols with CO2 provides linear β,γ-unsaturated carboxylic acids as
the sole regioisomer with generally high E/Z stereoselectivity. In
addition, the carboxylic acids can be generated from propargylic alcohols via a
hydrogenation step made possible by a Ni hydride intermediate produced by a
hydrogen atom transfer from water.
Y.-G. Chen, B. Shuai, C. Ma, X.-J. Zhang, P. Fang, T.-S. Mei, Org. Lett.,
2017, 19, 2969-2972.
In the presence of a Cu(I)/NHC catalyst, highly regioselective reactions of
allylboronic pinacol esters with CO2 (1 atm) give exclusively the
more substituted β,γ-unsaturated carboxylic acids in most cases. Various
substituted carboxylic acids can be prepared via this method, including
compounds featuring all-carbon quaternary centers.
H. A. Duong, P. B. Huleatt, Q.-W. Tan, E. L. Shuying, Org. Lett., 2013,
15, 4034-4037.
Exposure of N-acyloxyphthalimides (redox-active esters) to
galvanostatic electroreductive conditions enables a general regio- and
stereoselective alkylation of Morita-Baylis-Hillman compounds in high yields.
The method offers wide functional group tolerance.
G. Bertuzzi, G. Ombrosi, M. Bandini, Org. Lett.,
2022, 24, 4354-4359.
A Ni-catalyzed regiodivergent reductive carboxylation of allyl esters with CO2
is mild, user-friendly, and operationally simple. The reaction is characterized
by an exquisite selectivity profile that is dictated by the ligand backbone.
T. Moragas, J. Cornella, R. Martin,
J. Am. Chem. Soc., 2014,
136, 17702-17705.
A Ni-catalyzed regiodivergent reductive carboxylation of allyl esters with CO2
is mild, user-friendly, and operationally simple. The reaction is characterized
by an exquisite selectivity profile that is dictated by the ligand backbone.
T. Moragas, J. Cornella, R. Martin,
J. Am. Chem. Soc., 2014,
136, 17702-17705.
A direct, palladium-catalyzed, carbonylative transformation of allylic alcohols
in the presence of formic acid as the CO source provides β,γ-unsaturated
carboxylic acids with excellent linear and (E)-selectivity under mild
conditions.
F.-P. Wu, J.-B. Peng, L.-Y. Fu, X. Qi, X.-F. Wu, Org. Lett.,
2017, 19, 5474-5477.
An addition of tertiary carbon radicals generated by an Ir-catalyzed
visible-light photocatalyst to electron-deficient 1,3-dienes proceeds in good
yields. The reaction appends a δ-substituted β,γ-unsaturated carbonyl fragment
to a tertiary alcohol or carboxylic acid precursor and constructs a new
quaternary carbon center.
S. Y. Abbas, P. Zhao, L. E. Overman, Org. Lett.,
2018, 20, 868-871.
Formate salts can serve as hydride as well as a CO2 source in a mild
PGeP-palladium complex-catalyzed hydrocarboxylation of allenes through a highly
efficient decarboxylation-carboxylation process.
C. Zhu, J. Takaya, N. Iwasawa, Org. Lett.,
2015,
17, 1814-1817.
With K2S2O8 as the oxidant and AgNO3
as the catalyst, direct decarboxylative radical allylation of aliphatic
carboxylic acids with allyl sulfones in aqueous CH3CN solution gave
the corresponding alkenes in good yields under mild conditions. This
site-specific allylation method exhibits wide functional group compatibility.
L. Cui, H. Chen, C. Liu, C. Li, Org. Lett.,
2016, 18, 2188-2191.
Morita-Baylis-Hillman Reaction of α,β-Unsaturated Ketones with Allylic
Acetates by the Combination of Transition-Metal Catalysis and Organomediation
Y.-Q. Li, H.-J. Wang, Z.-Z. Huang, J. Org. Chem.,
2016,
81, 4429-4433.
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.
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.
Allylsilylation allows to install both silyl and allyl groups onto a
carbon-carbon double bond directly. Proton-exchanged montmorillonite showed
excellent catalytic performances for the allylsilylation of alkenes. Isolation
of the reaction intermediate on the montmorillonite surface helped to
investigate the reaction mechanism.
K. Motokura, S. Matsunaga, A. Miyaji, Y. Sakamoto, T. Baba, Org. Lett., 2010,
12, 1508-1511.
Enantioselective copper-catalyzed allylic alkylations of Grignard reagents were
performed on allylic bromides with a protected hydroxyl or amine functional
group using Taniaphos as a ligand. The terminal olefin moiety in the products
can be transformed into various functional groups without racemization.
A. W. van Zijl, F. López, A. J. Minnaard, B. L. Feringa, J. Org. Chem., 2007,
72, 2558-2563.
A chemo- and regioselective, Cu-catalyzed asymmetric addition of Grignard
reagents to 3-bromopropenyl esters provides allylic esters in high yields
and enantioselectivities using Taniaphos as ligand. The method is a
practical route to chiral, nonracemic allylic alcohols.
K. Geurts, S. P. Fletcher, B. L. Feringa, J. Am. Chem. Soc., 2006,
128, 15572-15573.
The use of catalytic loadings of picolinaldehyde and Ni(II) salts in catalytic
α-allylation of unprotected amino acid esters induces preferential reactivity at
the enolizable α-carbon over the free nitrogen with electrophilic palladium
π-allyl complexes to produce α-quaternary α-allyl amino acid esters.
Additionally, the use of chiral ligands to access enantioenriched α-quaternary
amino acid esters from racemic precursors is demonstrated.
P. Fang, M. R. Chaulagian, Z. D. Aron, Org. Lett., 2012,
14, 2130-2133.
Chelated amino acid ester enolates are excellent nucleophiles for allylic
alkylations. With these enolates, even terminal π-allyl palladium complexes react
without significant isomerization.
K. Krämer, U. Kazmaier, J. Org. Chem., 2006,
71, 8950-8953.
A bis(diisopropylamino)cyclopropenimine-substituted bis-protonated proton sponge
can be used as a bifunctional phase-transfer catalyst. The catalyst operates
simultaneously as a hydrogen bond donor and a phase-transfer catalyst,
facilitating the movement of charged intermediates from the interface to the
organic phase.
L. Belding, P. Stoyanov, T. Dudding, J. Org. Chem.,
2016,
81, 553-558.
A direct catalytic enantioselective allylation of acyclic α-ketiminoesters
provides α-allyl-α-aryl and α-allyl-α-trifluoromethyl amino esters in excellent
isolated yield and with high optical purity in the presence of catalytic amounts
of indium(I) iodide and commercially available BOX-type ligands. The allylated
products are easily converted to enantiomerically enriched α-substituted proline
derivatives.
U. Bhakta, P. V. Kattamuri, J. H. Siitonen, L. B. Alemany, L. Kürti,
Org. Lett., 2019, 21, 9208-9211.
Efficient Addition of Allylsilanes to α,β-Enones Using Catalytic Indium and
Trimethylsilyl Chloride
P. H. Lee, D. Seomoon, S. Kim, K. Nagaiah, S. V. Damle, K. Lee, Synthesis,
2003, 2023-2026.
In a catalytic method for the regioselective allylation of α,β-unsaturated
aldehydes, the use of an air-stable diethanolamine-complexed boronic acid (DABO
boronate) as the allyl transfer reagent promotes conjugate addition over
1,2-addition. Various aryl- and alkyl-substituted enals provide δ,ε-unsaturated
aldehyde products in good yields under mild conditions.
P. C. Roest, N. W. M. Michel, R. A. Batey, J. Org. Chem.,
2016, 81, 6774-6778.
In a catalytic method for the regioselective allylation of α,β-unsaturated
aldehydes, the use of an air-stable diethanolamine-complexed boronic acid (DABO
boronate) as the allyl transfer reagent promotes conjugate addition over
1,2-addition. Various aryl- and alkyl-substituted enals provide δ,ε-unsaturated
aldehyde products in good yields under mild conditions.
P. C. Roest, N. W. M. Michel, R. A. Batey, J. Org. Chem.,
2016, 81, 6774-6778.
The use of unsaturated methylidene ketones in catalytic conjugate allylations
allows a significant expansion in substrate scope and occurs in a highly
enantioselective fashion in the presence of a Taddol-derived phosphinite ligand.
L. A. Brozek, J. D. Sieber, J. P. Morken, Org. Lett., 2011,
13, 995-997.
A nickel-catalyzed ring-opening allylation of cyclopropanols with allylic
carbonates provides δ,ε-unsaturated ketones in moderate to good yields
under mild and neutral conditions. The reaction displays linear selectivity for
both linear and branched acyclic allylic carbonates and is also applicable to
cyclic allylic carbonates.
Y. Sekiguchi, Y. Y. Lee, N. Yoshikai, Org. Lett., 2021, 23,
5993-5997.
The reaction of alkoxides with boron trichloride results in the generation
of cations that can be allylated in subsequent transformations. The absence
of Brønsted acids can make a significant difference in such syntheses.
G. W. Kabalka, M.-L. Yao, S. Borella, J. Am. Chem. Soc., 2006,
128, 11320-11321.
G. W. Kabalka, M.-L. Yao, S. Borella, J. Am. Chem. Soc., 2006,
128, 11320-11321.
An Ir-catalyzed enantioselective benzylation reaction of allylic
electrophiles can occur directly from aryl acetic acids via stereoselective
carbon-carbon bond formation followed by decarboxylation as the terminal event.
The absence of a highly basic nucleophile offers broad functional group
compatibility that would not be possible employing established protocols.
P. J. Moon, Z. Wei, R. J. Lundgren, J. Am. Chem. Soc.,
2018,
140, 17418-17422.
The combination of a halogen bond donor with trimethylsilyl halide is an
efficient cocatalytic system for a direct dehydroxylative coupling reaction of
alcohol with various nucleophiles, such as allyltrimethylsilane and
trimethylcyanide, to give the corresponding adduct in moderate to excellent
yields.
M. Saito, N. Tsuji, Y. Kobayashi, Y. Takemoto, Org. Lett.,
2015,
17, 3000-3003.
Raising the pKa Limit of "Soft" Nucleophiles in Palladium-Catalyzed Allylic
Substitutions: Application of Diarylmethane Pronucleophiles
S.-C. Sha, J. Zhang, P. J. Carroll, P. J. Walsh, J. Am. Chem. Soc., 2013,
135, 17602-17609.
Aryl aldehydes couple readily with allylmetals to afford haloallylated products
in the presence of boron trihalides. The reactions tolerate a variety of
functional groups. Simple aqueous workup of haloallylation reactions, followed
by treatment with 1,8-diazabicyclo[5.4.0]undec-7-ene, provides a straightforward
route to synthetically useful (E)-1,3-dienes.
M. P. Quinn, M.-L. Yao, G. W. Kabalka, Synthesis, 2011,
3815-3820.
Bifunctional vinylboroate/allylic acetate esters react with Grignard reagents to
form tertiary allylic boronates via an 'ate-mediated allylic substitution' (AMAS)
approach. The method tolerates a wide range of substrates and Grignard reagents.
B. A. Ondrusek, J. K. Park, D. T. McQuade, Synlett, 2014, 25,
217-220.
Various acetals or alcohols react with allyl(trimethyl)silane or
1-phenyl-2-(trimethylsilyl)acetylene in the presence of a catalytic amount of
the Brønsted acid o-benzenedisulfonimide under mild conditions to give
good yields of the allylated products. The catalyst can be easily recovered and
purified for use in further reactions.
M. Barbero, S. Bazzi, S. Cadamuro, S. Dughera, C. Piccinini, Synthesis, 2010,
315-319.
Allylic gem-dichlorides undergo regio- and enanantioselective
copper-catalyzed allylic alkylation with Grignard reagents to afford chiral Z-vinyl
chlorides. Subsequent Suzuki cross coupling reactions afford optically active
Z-alkenes and 1,3-cis,trans dienes.
M. Giannerini, M. Fañanás-Mastral, B. L. Feringa, J. Am. Chem. Soc., 2012,
134, 4108-4111.
A copper-catalyzed enantioselective defluoroalkylation of linear
1-(trifluoromethyl)alkenes with arylboronate-activated alkyl Grignard reagents
provides various gem-difluoroalkenes. Tetraorganoborate complexes
generated in situ were the key reactive species for this transformation.
M. Wang, X. Pu, Y. Zhao, P. Wang, Z. Li, C. Zhu, Z. Shi, J. Am. Chem. Soc.,
2018,
140, 9061-9065.
An organic photoredox-catalyzed gem-difluoroallylation of
α-trifluoromethyl alkenes with alkyl iodides provides gem-difluoroalkene
derivatives via C-F bond cleavage. This transition-metal-free transformation
utilizes a readily available organic dye (4CzIPN) as the sole photocatalyst and
N,N,N',N'-tetramethylethylenediamine as the radical activator.
S. Yan, W. Yu, J. Zhang, H. Fan, Z. Lu, Z. Zhang, T. Wang, J. Org. Chem., 2022, 87,
1574-1584.
An efficient photoredox catalytic radical addition/defluoroalkylation
coupling reaction between derivatives of primary amines and
trifluoromethyl-substituted alkenes provides a series of gem-difluoroalkenes
under visible light irradiation. This reaction offers a broad substrate scope
and good functional group tolerance.
B. Wang, C.-T. Wang, X.-S. Li, X.-Y. Liu, Y.-M. Liang, Org. Lett.,
2022, 24, 6566-6570.
An efficient photoredox catalytic radical addition/defluoroalkylation
coupling reaction between derivatives of primary amines and
trifluoromethyl-substituted alkenes provides a series of gem-difluoroalkenes
under visible light irradiation. This reaction offers a broad substrate scope
and good functional group tolerance.
B. Wang, C.-T. Wang, X.-S. Li, X.-Y. Liu, Y.-M. Liang, Org. Lett.,
2022, 24, 6566-6570.
Zn mediates a decarboxylative/defluorinative alkylation of α-trifluoromethyl
alkenes with N-hydroxyphthalimide esters as radical precursors. Several
α-trifluoromethyl alkenes were readily coupled to a wide range of primary,
secondary, and tertiary radicals, affording the desired gem-difluoroethylenes
in good yields.
H.-W. Du, Y. Chen, J. Sun, Q.-S. Gao, H. Wang, M.-D. Zhou, Org. Lett., 2020, 22, 9342-9345.
In the “deacylative allylation”, the coupling partners, ketone pronucleophiles
and readily available allylic alcohols undergo in situ retro-Claisen activation
to generate an allylic acetate and a carbanion. In the presence of palladium,
these reactive intermediates undergo catalytic coupling to form a new C-C bond.
A. J. Grenning, J. A. Tunge, J. Am. Chem. Soc., 2011,
133, 14785-14794.
α-Halonitriles react with alkyllithium, organomagnesium, and lithium
dimethylcuprate reagents generating reactive, metalated nitriles. The rapid
halogen-metal exchange with alkyllithium and Grignard reagents allows
Barbier-type reactions with various electrophiles.
F. F. Fleming, Z. Zhang, W. Liu, P. Knochel, J. Org. Chem., 2005,
70, 2200-2005.
α-Cyano aldehydes undergo selective transition-metal-catalyzed allylation to
provide α-allylated nitriles. The transformation leads to linear allylated
nitriles with palladium catalysts whereas an iridium catalyst provides branched
substitution products. TBD-catalyzed retro-Claisen cleavage is leveraged to
attain selective monoallylation.
T. Maji, J. A. Tung, Org. Lett.,
2014,
16, 5072-5075.
Pd-catalyzed asymmetric allylic alkylation of nitroalkanes and monosubstituted
allylic substrates affords products with two adjacent chiral centers in
excellent regio-, diastereo-, and enantioselectivities. Products can be
transformed to optically active homoallylamines, 2,3-disubstituted
tetrahydropyridines, and α,β-disubstituted amino acid derivatives.
X.-F. Yang, W.-H. Yu, C.-H. Ding, Q.-P. Ding, S.-L. Wan, X.-L. Hou, L.-X. Dai,
P.-J. Wang, J. Org. Chem., 2013,
78, 6503-6509.
Allyl nitroacetates undergo decarboxylative allylation to provide tertiary
nitroalkanes in high yield within several minutes under ambient conditions. The
preparation of substrate allyl nitroacetates by tandem Knoevenagel/Diels-Alder
sequences allows the facile synthesis of relatively complex substrates that
undergo diastereoselective decarboxylative allylation.
A. J. Grenning, J.A. Tunge, Org. Lett., 2010,
12, 740-742.
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.
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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.
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,
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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,
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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.
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A nucleophilic allylation of acylsilanes in water provides versatile
functionalized tertiary α-silyl alcohols in high yields with the assistance of
hydrogen bonding. Unlike the conventional strategy, transition metals and an
additional Lewis acid catalyst were not required.
X.-X. Liang, C. Zhu, W. Zhang, Y.-N. Du, L. Xu, L. Liu, Y. Zhang, M.-Y. Han, J. Org. Chem., 2023, 88,
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A modular, practical,
and general palladium-catalyzed, radical three-component coupling enables selective
1,4-difunctionalization of unactivated 1,3-dienes, such as butadiene, by employing different commercially available nitrogen-, oxygen-,
sulfur-, or carbon-based nucleophiles and unactivated alkyl bromides.
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A Rh/silane-cocatalyzed regio- and enantioselective allylic cyanomethylation
with inert acetonitrile directly provides mono- and bis-allylation products by adjusting the size of substituents on the silane, ligands,
and temperature. Addition of a catalytic amount neutral silane reagent as an
acetonitrile anion carrier is essential for the success of this reaction.
M. Sun, L. Wei, C. Li, J. Am. Chem. Soc.,
2023, 145, 3897-3902.
A Rh/silane-cocatalyzed regio- and enantioselective allylic cyanomethylation
with inert acetonitrile directly provides mono- and bis-allylation products by adjusting the size of substituents on the silane, ligands,
and temperature. Addition of a catalytic amount neutral silane reagent as an
acetonitrile anion carrier is essential for the success of this reaction.
M. Sun, L. Wei, C. Li, J. Am. Chem. Soc.,
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Asymmetric allylic substitution with organolithium reagents enables a highly
regio- and enantioselective desymmetrization of meso-1,4-dibromocycloalk-2-enes
to afford enantioenriched bromocycloalkenes. The cycloheptene products undergo
an unusual ring contraction.
S. S. Goh, S. Guduguntly, T. Kikuchi, M. Lutz, E. Otten, M. Fujita, B. L.
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140, 7052-7055.
Enantioselective Allylic Carbon-Carbon Bond Construction |