Disclosed are electrochemical methods to prepare an alkane or an alkene, such as a cis- alkene, from an alkyne, or an alkane from an alkene. The method utilizes an electrochemical cell having a cathode and an anode and a reactor.
Allylic PMB ethers rearranged in the presence of zeolite beta to form 4-arylbutanals or 5-arylpentanones depending on the substituent pattern of the allylic moiety. Best results were obtained with substrates carrying simple substituents in the allylic 2-position, but a couple of substrates lacking a 2-substituent also rearranged. More functionalized substituents in this position were not tolerated. A propargyl PMB ether and a homoallylic PMB ether rearranged as well, but the products were mixtures of isomeric olefins. The 4-arylbutanals 2c and 2e and the 5-arylpentanone 2j were cyclized in PPA to give naphthalene and dihydronaphthalene derivatives, respectively.
Approach towards C12 oxo analogues of the side chain of pumiliotoxin B/allopumiliotoxin 339A and B
作者:John M. Gardiner、Philip E. Giles、Marı́a Luz Martı́n Martı́n
DOI:10.1016/s0040-4039(02)01071-7
日期:2002.7
A route towards the synthesis of analogues of pumiliotoxin and allopumiliotoxin side-chain is described. The C I 5,C 16 diol was introduced by asymmetric dihydroxylation using AD-mix beta of C10,C17 enynone intermediate 14, or of C13,C17 precursor 17, or by using a chiron-based route from 24. The trisubstituted alkene functionality was established using arylthio conjugate addition to ynones 16 and 27, followed by a copper-catalyzed stereoretentive reaction with methylmagnesium bromide. The approach enables access to C12 oxo systems and offers an approach towards new C14 analogues. (C) 2002 Elsevier Science Ltd. All rights reserved.
MIKAMI, K.;KIMURA, Y.;KISHI, N.;NAKAI, T., J. ORG. CHEM., 1983, 48, N 2, 279-281
作者:MIKAMI, K.、KIMURA, Y.、KISHI, N.、NAKAI, T.
DOI:——
日期:——
A Mild and Selective Cleavage of<i>p</i>-Methoxybenzyl Ethers by CBr<sub>4</sub>-MeOH
作者:J. S. Yadav、B.V. Subba Reddy
DOI:10.1246/cl.2000.566
日期:2000.5
p-Methoxybenzyl ethers were selectively deprotected to the corresponding alcohols and phenols in high yields by CBr4 in refluxing methanol under neutral reaction conditions.