威索霉素C2及其同类物C2a的合成已由sisomicin依赖于烯丙基叠氮化物向相应的α,β-不饱和醛的新型氧化转化以及其立体控制的精制成维达霉素C2和C2a的预期5'侧链。体外抗菌测试表明,维达霉素C2和C2a中的C6'差向异构体均对多种细菌菌株具有同等活性。2-取代的二氢[2 H ]吡喃的烯丙基伯叠氮化物,醚和酯与SeO 2的氧化直接导致相应的醛。
Syntheses of Seven-Membered Rings: Ruthenium-Catalyzed Intramolecular [5+2] Cycloadditions
作者:Barry M. Trost、Hong C. Shen、Daniel B. Horne、F. Dean Toste、Bernhard G. Steinmetz、Christopher Koradin
DOI:10.1002/chem.200401065
日期:2005.4.8
The Ru-catalyzed intramolecular [5+2] cycloaddition of cyclopropylenynes is investigated with respect to the regio- and diastereoselectivity as well as the functional group compatibility of the reaction. Evidence for the mechanism as occurring through a ruthenacyclopentene intermediate is elucidated from 1) the study of the diastereoselectivity of the cycloaddition; 2) the effect of variation of substituents
A new class of adenosine analogues with 1,2-disubstituted carbocycles (with cis and trans stereochemistry) have been synthesized. Construction of the base on the amino group of (+/-)-cis-(2-aminocyclohexyl)methanol was more efficient than the Mitsunobu condensation between the purine base and protected (+/-)-trans-(2-hydroxymethyl)cyclohexanol. The latter strategy gave the final compound with cis stereochemistry in a short number of steps with the overall yield depending on the nature of the protecting group on the hydroxymethyl group of the diol. However, Mitsunobu condensation between a purine base and the protected (+/-)-cis-(2-hydroxymethyl)cyclohexanol is not an ideal method to obtain trans purine derivatives because the elimination reaction is faster than the substitution reaction. (C) 2004 Elsevier Ltd. All rights reserved.
Electrophilic conversion of oxiranes to allylic alcohols with tert-butyldimethylsilyl iodide