Enantioselective Claisen Rearrangements: Development of a First Generation Asymmetric Acyl-Claisen Reaction
作者:Tehshik P. Yoon、David W. C. MacMillan
DOI:10.1021/ja015612d
日期:2001.3.1
The development of an enantioselective catalytic Claisenrearrangement remains an important yet elusive goal in chemical synthesis. With this objective in mind, we recently reported the acyl-Claisen rearrangement, a Lewis acid-catalyzed variant of the Bellus reaction that utilizes acid chlorides and allylic amines in the stereoselective synthesis of ɑ,β-disubstituted-y,δ-unsaturated carbonyls (eq 1)
Synthesis of γ-Amino Esters via Mn-Mediated Radical Addition to Chiral γ-Hydrazonoesters
作者:Gregory K. Friestad、Koushik Banerjee
DOI:10.1021/ol802932v
日期:2009.3.5
Highly stereoselective Mn-mediated couplings of alkyl iodides with chiral N-acylhydrazones bearing ester functionality afford a series of gamma-hydrazino esters, including gamma-substituted, alpha,gamma-disubstituted, and alpha,alpha,gamma-trisubstituted examples. In contrast to prior work with chiral N-acylhydrazones, high stereoselectivity was observed even in the absence of Lewis acid. Microwave-assisted acylation with trifluoroacetic anhydride and reductive N-N bond cleavage provided the gamma-amino ester functionality in a synthetically useful N-TFA-protected form.