... 1965,8, 676. (5) West, P. R.; Warkentin, J. J. Org. Chem. ... (1) Ulrich, H. 'Cycloaddition Reactions of Heterocumulenes", Organic Chemistry, A Series of Monographs; Blomquist, AT, Ed.; Academic Press: New York and London, 1967; Vol. 9, pp 122-220. ... Chem. 1969, 724, 226. ...