... Intermediacy of a Cyclobutadiene Derivative and Its Trapping by Methanol Takashi TSUJI* and Shinya NISHIDA Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060 ... References 1) T. Tsuji and S. Nishida, Tetrahedron Lett., 24, 1269 (1983). 2) The preparation of lb was achieved by modifying the synthetic procedure for la; T. Tsuji and S. Nishida, Tetrahedron Lett., 24, 3361 (1983). 3) G. Maier and W. Sauer, Angew. Chem., Int. ...