the Beckmann fragmentation of alpha-alkoxy and alpha-alkoxy-alpha-alkyl oxime acetates have been successfully trapped as phosphonium salts, which were subsequently reacted with a variety of Grignard reagents to give the corresponding substituted products in good yields. Notably, this reaction proceeded smoothly even from alpha-alkoxy-alpha-alkyl oxime acetates.
Cation−n Control of Regiochemistry of Intramolecular Schmidt Reactions en Route to Bridged Bicyclic Lactams
作者:Michal Szostak、Lei Yao、Jeffrey Aubé
DOI:10.1021/ol901771b
日期:2009.10.1
The regiochemistry of the intramolecular Schmidt reaction of 2-azidoalkylketones is controlled by placing a thioether substituent at the position adjacent to the ketone to provide access to a family of unsubstituted medium bridged twisted amides. This outcome is ascribed to the presence of stabilizing through-space interactions between the diazonium cation and the n electrons on heteroatom and does
Total synthesis of ingenol, a diterpene isolated from the genus Euphorbia, was accomplished on the basis of the novel key reactions. The highly strained ingenane skeleton was constructed through an intramolecularcyclization reaction of an acetylene dicobalt complex followed by a rearrangement reaction of an epoxy alcohol. The C(3),C(4),C(5)-triol moiety was introduced by a stereoselective double dihydroxylation