Regioselective Synthesis of Functionalized Furans by Cyclization of 1,3‐Bis‐Silyl Enol Ethers with 1‐Chloro‐2,2‐dimethoxyethane

Cyclization of 1,3‐bis‐silyl enol ethers with 1‐chloro‐2,2‐dimethoxyethane allowed an efficient, regio‐ and diastereoselective synthesis of a variety of 2‐alkylidene‐4‐methoxytetrahydrofurans. The TFA‐mediated elimination of methanol resulted in the formation of functionalized furans. Similarly, 2,3,3a,4,5,6‐hexahydro‐2,3‐benzofurans were prepared and transformed into 4,5,6,7‐tetrahydro‐2,3‐benzofurans by treatment with TFA. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)