(α-Alkylation of α-heterosubstituted carboxylic acids without racemization
作者:Dieter Seebach、Reto Naef、Giorgio Calderari
DOI:10.1016/s0040-4020(01)82417-0
日期:1984.1
α-Hydroxy- and α-mercapto-carboxylic acids are condensed with pivalaldehyde to give 2-t-butyl-5-substituted-l,3-dioxolanones or 1,3-oxathiolanones (2); the predominate CK-isomers are separated by crystallization. The cis-disubstituted heterocycles 2 derived from lactic, mandelic and malic acid furnish, after deprotonation with LDA, reaction with electrophiles such as alkyl halides, aldehydes and ketones
Studies in stereoselective [2+2]-cycloadditions with dichloroketene
作者:David I. MaGee、Tammy C. Mallais、Peter D.M. Mayo、George M. Strunz
DOI:10.1016/j.tet.2006.02.014
日期:2006.4
During the investigation of the reaction of dichloroketene with cyclic enoxy-lactones and acyclic enoxy-ester substrates it was found that only the acylic variants effectively participated in the [2+2]-cycloaddition. Although a complete understanding of the reasons for this are lacking, molecular mechanics calculations do suggest that an out of plane twist of the cabonyl group in the acyclic compounds