A Practical Synthesis of Polyhalomethyllithium-Carbonyl Adducts
作者:Hiroaki Taguchi、Hisashi Yamamoto、Hitosi Nozaki
DOI:10.1246/bcsj.50.1588
日期:1977.6
of a mixture of polyhalomethane and a carbonylcompound with a hindered lithium amide. The kinetically controlled, selective lithiation of the halide enables us to avoid a troublesome procedure involving preformed lithiumcarbenoid. The halide components examined are dichloromethane, dibromomethane, diiodomethane, chloroform, and bromoform, while the carbonyl ones are ubiquitous ketones and nonanal
Preparation of alkenesvia a manganate-induced alkylation–elimination sequence was investigated. The reaction of 2-alkoxy-1,1-dibromoalkanes with trialkylmanganates afforded disubstituted or trisubstitutedalkenes. Treatment of 2-alkoxy-1,1,1-tribromoalkanes with trialkylmanganates provided trisubstituted or tetrasubstituted alkenes through bromine–metal exchange, transfer of two alkyl groups from
A convergent and stereoselectivesynthesis of vitaminD3 was achieved via3,5-cyclovitaminsD3 (20) which were prepared from the chiral aldehyde (2) and the vinyl bromide (12) derived from Grundmann's ketone.