Properties and Reactions of Substituted 1,2-Thiazetidine 1,1-Dioxides: Methylation of β-Sultams
作者:Martin Müller、Hans-Hartwig Otto
DOI:10.1002/ardp.19913240106
日期:——
Methylation of N‐substituted 1,2‐thiazetidine 1,1‐dioxides in the presence of lithium diisopropylamide (LDA) yields 4,4‐dimethyl derivatives. Monomethylation only occurs when one position at C‐4 is blocked by a silyl group, which, afterwards, can be removed by treatment with tetrabutylammonium fluoride (TBAF). A silyl protecting group at the nitrogen is easily removed by cleavage with TBAF on silica