Novel Dipolar Cycloaddition Reactions of Zwitterionic Species Generated from Dimethoxycarbene and Dimethyl Acetylenedicarboxylate with Carbonyl Compounds: Facile Synthesis of Dihydrofuran Derivatives - Nair, Vijay; Bindu, S; Sreekumar, V; Balagopal, Lakshmi (Synthesis, 2003)