Utility of a chiral 1,3-dioxane template in stereoselective intramolecular Diels–Alder reactions
摘要:
The ethylidene acetal Of D-erythrose was used as a template for stereoselective IMDA reactions: high endo selectivity and yields in favor of the cis product were observed with 1,3,9-trienes, resulting from a boat transition state. For natural product synthesis, the reaction was successfully applied to a diene with terminal Z-olefin. (c) 2007 Elsevier Ltd. All rights reserved.
asymmetric 1,3-dioxane template in intramolecularDiels-Alder reactions is reported. The 1,3,9-decatrienoates substrates gave predominantly the endo-boat products, with minor amounts of the exo-boat isomer. Various substitutions (14 examples) were introduced and the results gave an indication of the scope and also a few limitations of the method. In particular, the approach was applicable to (E,Z)-diene
Asymmetric Synthesis of the Oxygenated Polycyclic System of (+)-Harringtonolide
作者:Hajer Abdelkafi、Patrick Herson、Bastien Nay
DOI:10.1021/ol300133x
日期:2012.3.2
A straightforward asymmetric synthesis of the cage oxygenated structure of (+)-harringtonolide has been accomplished for the first time. The key steps involved (i) a templated stereoselective IMDA reaction to build a highly functionalized cyclohexene ring D, (ii) functionalization of the cycloadduct, (iii) ring-closing metathesis providing the five-membered ring C, and finally (iv) a challenging one-step cascade cyclization of an epoxy-alcohol toward the target structure, whose mechanism was investigated.