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Synthesis of Cyclic N ‐Tosyliminocarbonates by Lewis Acid Catalyzed Allylic Substitution of Trichloroacetimidates
Author(s) -
Grigorjeva Liene,
Jirgensons Aigars
Publication year - 2012
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201200378
Subject(s) - chemistry , allylic rearrangement , selectivity , catalysis , lewis acids and bases , medicinal chemistry , alkyl , aryl , alkylation , stereochemistry , carbamate , tsuji–trost reaction , organic chemistry
Allylic trichloroacetimidates bearing a δ‐ N ‐tosylcarbamoyloxy group were prepared in two steps from the corresponding diols, and their Brønsted and Lewis acid catalyzed cyclization reactions were investigated. It was found that N ‐tosylcarbamates derived from secondary and tertiary alcohols bearing alkyl substituents undergo a chemoselective allylic alkylation to give N ‐tosyliminocarbonates in good isolated yields. In turn, aryl‐substituted substrates tend to give oxazolines by abstraction of the carbamate functionality. The cyclization of N ‐tosylcarbamates derived from secondary alcohols preferentially give trans ‐iminocarbonates. However, the trans selectivity varied and depended on the substitution pattern, configuration of the substrate, and the catalyst. A high trans selectivity could be achieved from ( E ) substrates by using TMSOTf as the catalyst. The synthetic utility of iminocarbonates was demonstrated by transforming them into 1,2‐diols and cyclic carbonates as well as into N ‐tosyloxazolidinones by a halide ion‐induced rearrangement.