Two-flask preparation of .alpha.-lithio cyclic ethers from .gamma.- and .delta.-lactones. Reductive lithiation as a route, via radical intermediates, to axial 2-lithiotetrahydropyrans and their equilibration to the equatorial isomers
作者:Theodore Cohen、Ming Teh Lin
DOI:10.1021/ja00316a060
日期:1984.2
Application a la synthese du rose oxyde et de perhydro furannes, -pyrannes et -chromannes substitues en 2
应用 a la synthese du rose oxyde et de perhydrofuranes, -pyrannes et -chromannes substitues en 2
The stereospecific synthesis ofcis andtrans 1-oxabicyclo[4,4,0]decanes and 9-methoxycarbonyl-1-oxabicyclo[4,3,0]nonanes
作者:D. Neville Jones、M. Akram Khan、Sohail M. Mirza
DOI:10.1016/s0040-4020(99)00532-3
日期:1999.8
The allylic sulphoxides1b and1e reacted with 1-pyrrolidinylcyclohexene and 2-ethoxycarbonyl cyclopentanone to yield the 2-substituted keto-sulphoxides10 and14 respectively, which on reduction followed by oxidation yielded in each case a mixture ofcis andtrans sulphones that were separated by column chromatography. Base induced cyclisation followed by reductive desulphurisation of the cyclised sulphones
Stereochemical editing logic powered by the epimerization of unactivated tertiary stereocenters
作者:Yu-An Zhang、Vignesh Palani、Alexander E. Seim、Yong Wang、Kathleen J. Wang、Alison E. Wendlandt
DOI:10.1126/science.add6852
日期:2022.10.28
The stereoselective synthesis of complex targets requires the precise orchestration of chemical transformations that simultaneously establish the connectivity and spatial orientation of desired bonds. In this work, we describe a complementary paradigm for the synthesis of chiral molecules and their isomers, which tunes the three-dimensional structure of a molecule at a late stage. Key to the success
Cyanomethylenetributylphosphorane was shown to mediate the dehydrocyclization of diols and amino alcohols to give the corresponding 6-membered O- and N-heterocycles in 90% or better yields. Using the reaction as a key step, (+)-alpha-skytanthine, a unique mono terpene alkaloid was synthesized stereoselectively. Copyright (C) 1996 Elsevier Science Ltd