Synthesis of Chiral α,β-Unsaturated γ-Amino Esters via Pd-Catalyzed Asymmetric Allylic Amination
作者:Chao Xia、Jiefeng Shen、Delong Liu、Wanbin Zhang
DOI:10.1021/acs.orglett.7b01904
日期:2017.8.18
A Pd-catalyzed asymmetricallylic amination of 4-substituted 2-acetoxybut-3-enoates with amines has been developed for the regiospecific synthesis of chiral α,β-unsaturated γ-amino esters. The desired chiral aminated products can be obtained in up to 98% yield, and 99% ee and can be conveniently transformed to chiral γ-amino acid/alcohol derivatives and chiral γ-lactams, which can then be subjected
Regiochemical control in the preparation of 2-(nosyloxy) .beta.,.gamma.-unsaturated esters and 4-(nosyloxy) .alpha.,.beta.-unsaturated esters from 1-[(trimethylsilyl)oxy]-1-alkoxy 1,3-dienes
作者:Robert V. Hoffman、Hwa Ok Kim
DOI:10.1021/jo00003a022
日期:1991.2
A series of 1-[(trialkylsilyl)oxy]-1-alkoxy 1,3-dienes 1a-i were found to react with p-nitrobenzenesulfonyl peroxide in the presence of sodium methoxide or zinc chloride to give alkyl 2-[[(p-nitrophenyl)sulfonyl]oxy] beta-gamma-unsaturated esters 3 and alkyl 4-[[(p-nitrophenyl)sulfonyl]oxy] alpha,beta-unsaturated esters 4 which are readily separable. The regioselectivity is determined by kinetic versus thermodynamic control. When positions 2 or 4 of the diene are unsubstituted, the 2-isomer is the major product and is the kinetically fastest formed product. It can be thermally rearranged to the more stable 4-isomer. When alkyl substituents are present at either the 2- or 4-positions, only the 4-isomer is obtained. Substitution for nosylate by amine nucleophiles occurs by an S(N)2 process. Thus 2-amino beta,gamma-unsaturated esters and 4-amino alpha,beta-unsaturated esters can be prepared from the appropriate starting nosylate.
HOFFMAN, ROBERT V.;KIM, HWA-OK, J. ORG. CHEM., 56,(1991) N, C. 1014-1019
作者:HOFFMAN, ROBERT V.、KIM, HWA-OK
DOI:——
日期:——
TANIKAGA RIKUHEI; TAKEUCHI JUN; TAKYU MASAYUKI; KAJI ARITSUNE, J. CHEM. SOC. CHEM. COMMUN.,(1987) N 5, 386-387
Palladium(0)-catalysed reactions of 4-chloroacetoxyalk-2-enoicesters with amines selectively give 4-aminoalk-2-enoic esters, which are readily converted into pyrrol-2(5H)-ones (4-but-2-enelactams).