Synthesis of multisubstituted 2-(dihydrofuran-2(3H)-ylidene)acetates via intramolecular carboalkoxylation by platinum-olefin catalyst system.
The cyclization of 6-(1-alkoxyethyl)hex-2-ynoates in the presence of a 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 led to the Z isomer, while the phenyl ester gave the E isomer.