Stereochemical Control by an Ester Group or Olefin Ligand in Platinum-Catalyzed Carboalkoxylation of 6-(1-Alkoxyethoxy)- hex-2-ynoates
作者:Itaru Nakamura、Ching Siew Chan、Toshiharu Araki、Masahiro Terada、Yoshinori Yamamoto
DOI:10.1002/adsc.200800772
日期:2009.5
Abstractmagnified imageThe cyclization of 6‐(1‐alkoxyethoxy)hex‐2‐ynoantes in the presence of the platinum‐olefin catalyst system gave the corresponding multisubstituted 2‐[dihydrofuran‐2(3H)‐ylidene]acetates in good to high yields. The Z/E selectivity is controlled by the electronic property of the ester group; the 2,2,2‐trichloroethyl ester yielded the Z isomer, while the phenyl ester gave the E isomer. Moreover, we found that the Z/E selectivities in the reaction of phenyl esters 1h, 1n, and 1o were controlled by the olefin ligand. For example, the platinum‐catalyzed reaction of 1h using 1,5‐hexadiene as the olefin ligand gave E‐2h as the major product, while that using 1,5‐cyclooctadiene produced mainly the Z isomer.