A General Method for the Highly Regioselective Introduction of Substituents into the 3-Position of 5-Unsubstituted 4-O-Alkyl Tetronates

A new, general method for the highly regioselective introduction of substituents into the 3-position of 5-unsubstituted 4-O-alkyl tetronates has been developed. 3-Lithiated 4-alkoxy-2-tri-isopropylsilyloxyfurans generatedfrom the corresponding 3-iodoprecursors via halogen-metal exchange serve as key intermediates.