Categories: C-C Bond Formation > Nitrogen-containing molecules > Synthesis of amines >
Synthesis of Homoallylamines
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A general and mild CuCl-TBAT-catalyzed allylation of aldehydes, ketones, and
imines was developed using allyltrimethoxysilane as the allylating reagent.
Mechanism studies indicated that the copper alkoxide,
allylfluorodimethoxysilane, and allyltrimethoxysilane are essential to
promote the reaction efficiently.
S. Yamasaki, K. Fujii, R. Wada, M. Kanai, M. Shibasaki, J. Am. Chem. Soc.,
2002,
124, 6536-6537.
Stoichiometric KOtBu in THF enables an efficient transition metal-free
approach for the generation of N-unsubstituted imines from azides.
Trapping with allyl nucleophile provides N-unsubstituted homoallylic
amines. Further, an enantio- and diastereoselective synthesis of homoallylic
amines from benzyl azide has also been exemplified.
S. Pramanik, R. R. Reddy, P. Ghorai, J. Org. Chem.,
2015,
80, 3656-3663.
Triallylborane-amine adducts can be used as stoichiometric allylating
agents for efficient aminoallylation reactions of carbonyl compounds in methanol.
Moreover, copper catalysis enables a diastereoselective allylation of Ellman’s
imine.
N. Y. Kuznetsov, R. M. Tikhov, T. V. Strelkova, Y. N. Bubnov, Org. Lett.,
2018, 20, 3549-3552.
A Rh-catalyzed asymmetric allylation of
aliphatic aldimines provides optically active
1-alkyl homoallylic amines in good yields and very good ee under
mild, aqueous reaction conditions. The preparation of indolizidine and piperidine alkaloids demonstrates
the
usefulness of this method.
W.-S. Li, T.-S. Kuo, M.-C. Hsieh, M.-K. Tsai, P.-Y. Wu, H.-L. Wu,
Org. Lett., 2020, 22, 5675-5679.
Sulfonimines derived from nonenolizable aldehydes can be effectively allylated to the corresponding homoallylic
sulfonamides with allylic bromides promoted by indium or zinc. The
stereoselectivity and regioselectivity of the reactions were examined.
W. Lu, T. H. Chan, J. Org. Chem., 2000,
65, 8589-8594.
A combination of a photoredox and a palladium catalyst catalyzes a
dehydrative coupling reaction of alkyl amines with allylic alcohols to provide a
range of homoallylic amines.
Y. Masuda, M. Ito, M. Murakami,
Org. Lett., 2020, 22, 4467-4470.
BF3·Et2O promotes an interrupted Schmidt rearrangement/Hosomi-Sakurai reaction of
N-tosyl vinyl azides via denitrogenative fragmentation, generation of
a stabilized carbocation, which further undergoes nucleophilic addition by
allyl/propargylsilanes for C-C bond formation. The reaction provides various homoallylic/allenylic amines in good yields under mild reaction
conditions with well-defined functional-group tolerance.
G. Fang, Z. Liu, S. Cao, H. Yuan, J. Zhang, L. Pan, Org. Lett.,
2018, 20, 7113-7116.
A palladium complex catalyzes two transformations in one pot: formation of
allylsilane from allyl trifluoroacetate using hexamethyldisilane and subsequent
imine allylation. A three-component reaction was developed where preformed
imines were replaced with aldehydes and anisidine. Under these reaction
conditions various aldehydes react smoothly to afford homoallylic amines.
R. E. Grote, E. R. Jarvo, Org. Lett., 2009,
11, 485-488.
An asymmetric Rh-catalyzed 1,2-allylation of N-Ts- and N-Ns-aldimines
with potassium allyltrifluoroborates generates enantioenriched homoallylic
amines in very good yields with very good enantioselectivities. Using subsituted
allyltrifluoroborates, high diastereoselectivity is achieved. Reactions of both
potassium (E)- and (Z)-crotyltrifluoroborates provide the same
diastereomer.
P. F. Chiang, W.-S. Li, J.-H. Jiang, T.-S. Kuo, P.-Y. Wu, H.-L. Wu, Org. Lett.,
2018, 20, 158-161.
Readily accessible N-(aryloxy)imines undergo efficient allylation to
afford a wide range of homoallylic primary amines following hydrolytic workup.
Deprotonation of N-(aryloxy)imines generates a delocalized 2-azaallyl
anion-type nucleophile that engages in dearomative unselective allylation
followed by [1,3]- or concerted [3,3]-sigmatropic shifts to provide the desired
products.
L. M. Mori-Quiroz, S. S. Londhe, M. D. Clift, J. Org. Chem., 2020, 85, 14827-14846.
An enantioselective synthesis of homoallylamides through reactions of stable and
easily accessible (pinacolato)allylborons with aryl-, heteroaryl-, alkyl-, or
alkenyl-substituted N-phosphinoylimines is promoted by 1-5 mol % of
readily accessible NHC-Cu complexes, derived from C1-symmetric
imidazolinium salts. Allyl additions deliver the desired products in very good
yield and enantiomeric ratio.
E. M. Vieira, M. L. Snapper, A. H. Hoveyda, J. Am. Chem. Soc., 2011,
133, 3332-3335.
An iridium-catalyzed asymmetric umpolung allylation of imines provides
1,4-disubstituted homoallylic amines via a sequence involving an intermolecular
regioselective allylation of 2-azaallyl anions followed by a 2-aza-Cope
rearrangement. The reaction utilizes easily available reagents and catalysts,
tolerates a substantial scope of substrates, and readily leads to various
enantioenriched, 1,4-disubstituted homoallylic primary amines.
J. Liu, C.-G. Cao, H.-B. Sun, X. Zhang, D. Niu, J. Am. Chem. Soc., 2016,
138, 13103-13106.
The catalytic use of a sodium amide enables a formal allylic C(sp3)-H
bond activation of alkenes under mild conditions. Subsequent C-C bond formations
with imines have proceeded in high yields with complete regioselectivity and
excellent geometric selectivity.
W. Bao, H. Kossen, U. Schneider, J. Am. Chem. Soc., 2017,
139, 4362-4365.
A highly α-regioselective prenylation of imines enables the conversion a wide
range of substrates including N- and C-aryl aldimines, N-alkyl
aldimines, C-alkyl aldimines, and N- and C-aryl ketimines.
The approach uses prenyl bromide as prenyl source and inexpensive zinc as
mediator as well as environmentally benign 1,3-dimethyl-2-imidazolidinone (DMI)
as solvent.
L.-M. Zhao, S.-Q. Zhang, H.-S. Jin, L.-J. Wan, F. Dou, Org. Lett., 2012,
14, 886-889.
Aromatic aldehydes can be converted to α-amino anion equivalents via amination
with 2,2-diphenylglycine and subsequent decarboxylation. These in situ generated
α-imino anions are highly reactive for Pd-catalyzed allylation to give
homoallylic amines in high yields with excellent regioselectivity.
L. Ding, J. Chen, Y. Hu, J. Xu, X. Gong, D. Xu, B. Zhao, H. Li, Org. Lett., 2014,
16, 720-723.
A highly efficient three-component coupling reaction between thioformamides and
organolithium and Grignard reagents was developed. The generality of the process
has been demonstrated by using various combinations of reactants and reagents.
T. Murai, F. Asai, J. Am. Chem. Soc., 2007,
129, 780-781.
A mild and chemoselective double allylboration of nitriles and acid anhydrides
to form bis-allyl amines and esters, respectively, can be achieved through the
use of potassium allyltrifluoroborate in the presence of boron trifluoride
etherate at room temperature. The reaction with an operationally stable and
robust potassium organotrifluoroborate reagent avoids the use of metals.
T. R. Ramadhar, J. Bansagi, R. A. Batey, J. Org. Chem., 2013,
78, 1216-1221.
Homoallylic α-amino esters and amines were prepared via a Pd(II)-catalyzed
coupling of 1,2-nonadiene and boronic acids with ethyl iminoacetate or aliphatic,
aromatic, and heteroaromatic imines.
C. D. Hopkins, H. C. Malinakova, Org. Lett., 2006,
8, 5971-5974.
The combination of dirhodium(II)/Xantphos catalyzes a three-component
reaction of readily accessible amines, diazo compounds, and allylic compounds to
afford various architecturally complex and functionally diverse α-quaternary
α-amino acid derivatives in good yields with high atom and step economy.
B. Lu, X. Liang, J. Zhang, Z. Wang, Q. Peng, X. Wang, J. Am. Chem. Soc.,
2021, 143, 11799-11810.
2,2'-Dimorpholinodiethyl ether
(DMDEE) mediates a γ-selective addition of chloroprene Grignards to aromatic N-Boc aldimines
to provide the corresponding N-Boc protected β-allenylamines in good yields and regioselectivities.
Transmetalation to zinc bromide also allows the addition of chloroprene Grignard to aliphatic aldimines in good yields.
A. G. A. Geissler, B. Breit, Org. Lett., 2022, 24,
7967-7971.
An asymmetric vinylogous Mannich reaction of α,α-dicyanoolefins and
N-Boc
aldimines is promoted by a simple chiral bifunctional thiourea-tertiary amine
organocatalyst. The reaction was highly efficient, regio-, and stereoselective
at room temperature for a broad range of substrates.
T.-Y. Liu, H.-L. Cui, J. Long, B.-J. Li, Y. Wu, L.-S. Ding, Y.-C. Chen, J. Am. Chem. Soc., 2007,
129, 1878-1879.
Related
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.
