Asymmetric Syntheses of (2<i>R</i>,3<i>S</i>)-3-Hydroxyproline and (2<i>S</i>,3<i>S</i>)-3-Hydroxyproline
作者:Stephen G. Davies、Ai M. Fletcher、Sean M. Linsdall、Paul M. Roberts、James E. Thomson
DOI:10.1021/acs.orglett.8b01736
日期:2018.7.6
Two synthetic routes have been developed for the asymmetricsyntheses of (2R,3S)- and (2S,3S)-3-hydroxyproline. The key synthetic step in each of these strategies is the conversion of protected α,δ-dihydroxy-β-amino esters (either 2,3-anti- or 2,3-syn-configured) into β,δ-dihydroxy-α-amino esters (protected forms thereof), via the intermediacy of the corresponding aziridinium ions. The products of
A Diels-Alder approach to Stemona alkaloids: total synthesis of stenine
作者:Cheng Yi Chen、David J. Hart
DOI:10.1021/jo00067a015
日期:1993.7
A total synthesis of dl-stenine (4) is described. Key features involve (1) use of an intramolecular Diels-Alder cycloaddition-aminimide rearrangement sequence to construct the perhydroindole substructure (29 --> 36 --> 27), (2) application of an Eschenmoser-Claisen rearrangement-iodolactonization sequence to prepare the butenolide substructure (58 --> 59 --> 61), (3) use of a free-radical allylation to introduce the C(9)-ethyl group (61 --> 62), and (4) thermal cyclization of an amino ester to afford azepinone 68. A variety of intermolecular and intramolecular Diels-Alder reactions, including examples in which alpha,beta-unsaturated thioesters play the role of dienophile, are also described.