Metal-halogen exchange-initiated intramolecular conjugate addition reactions of conjugated acetylenic esters
摘要:
The lithium-iodine exchange-initiated intramolecular conjugate addition reactions of some model gamma-iodo-alpha,beta-acetylenic esters have been examined. Product mixtures arising from proton abstraction reactions were observed in reactions leading to 5-membered ring formation. More efficient cyclizations resulted when reactions were conducted in the presence of trimethylsilyl chloride to trap intermediate allenolate ions. Allenolate ion trapping by an internal electrophilic center in 26 resulted in the highly efficient formation of bicyclic ester 27.
Peterson olefination reaction using (trimethylgermyl)acetate. Stereoselective synthesis of (E)-2-alkenoic acid esters
作者:Sumie Inoue、Yoshiro Sato
DOI:10.1021/jo00001a064
日期:1991.1
Peterson-type reaction of (trimethylgermyl)acetates 1 with aldehydes and ketones 2 gave stereoselectively (E)-2-alkenoic acid esters (E)-4 after stirring at -78-degrees-C and warming to room temperature. High yields of the reaction intermediates threo- and erythro-3-hydroxy-2-(trimethylgermyl)alkanoic acid esters 3 were obtained when the reaction was quenched at -78-degrees-C. The paths for conversion of threo-3 and erythro-3 to (E)-4 are discussed.
INOUE, SUMIE;SATO, YOSHIRO, J. ORG. CHEM., 56,(1991) N, C. 347-352