Regio-, stereo-, and enantioselectivity in the electrophilic reactions of 2-amino-4-phenyl-3-butenenitriles
作者:Chih Jung Chang、Jim Min Fang、Li Fan Liao
DOI:10.1021/jo00059a027
日期:1993.3
The allylic anion generated from 2-(N-methylanilino)-4-phenyl-3-butenenitrile (1) reacted with iodomethane and 3-bromo-1-chloropropane in THF/HMPA to give the gamma-substitution products exclusively, predominantly in the 2Z-configuration. Substitution of the N-methylanilino group with the methyl ether of L-(-)-ephedrine resulted in the generation of chiral aminonitrile 2. Lithiated 2 reacted sluggishly in THF with allyl bromide and benzyl chloride in the absence of HMPA to give the gamma-substitution products predominantly in the 2Z-configuration, with little diastereoselectivity. The aminonitrile 3 prepared from cinnamaldehyde, L-(-)-ephedrine, and KCN was lithiated with 2 equiv of LDA resulting in high facial selectivity (76-100% diastereomeric excess) in alkylations in the presence of HMPA and LiI. Lithiated 3 reacted with propionaldehyde, benzaldehyde, and p-bromobenzaldehyde at-78-degrees-C to give the gamma-addition products, predominantly in the 4R-configuration (64-78% de). The stereochemistry of the isomers of each product was determined by chemical correlation and spectral methods including analyses of the CD spectra and X-ray diffraction. A bicyclic transition state C wherein lithium is chelated by both amino and alkoxy groups is proposed to interpret the observed stereoselectivity.
Chang Chih-Jung, Fang Jim-Min, Liao Li-Fan, J. Org. Chem., 58 (1993) N 7, S 1754-1761
作者:Chang Chih-Jung, Fang Jim-Min, Liao Li-Fan
DOI:——
日期:——
Applications of the amino-Cope rearrangement: synthesis of tetrahydropyran, δ-lactone and piperidine targets
作者:Steven M. Allin、Munira Essat、Catarina Horro Pita、Robert D. Baird、Vickie McKee、Mark Elsegood、Mark Edgar、David M. Andrews、Pritom Shah、Ian Aspinall
DOI:10.1039/b416179c
日期:——
We report a novel approach to some chiral tetrahydropyran and delta-lactone targets that utilizes the asymmetric amino-Cope rearrangement as a key synthetic step. Products of amino-Cope rearrangement chemistry have also been applied to access piperidine targets, further demonstrating the potential of the methodology.