SYN-ANTI SELECTIVITY OF CIS-3,4-DISUBSTITUTED CYCLOBUTENES Part 2: New Cycloadditions with Dichlorocyclobutene and an Interpretation in Terms of Vicinal Interactions in Transitions Structures

Article abstract of DOI:10.1016/S0040-4039(00)82405-3

Cycloaddition reactions of diazoalkanes, with R = H and R' = H, alkyl, aryl or alkoxycarbonil, yield syn-adducts with dichlorocyclobutene.Diphenylnitrilimine, however, mainly undergoes anti-additions.Two phenomena not described as yet will be discussed for the interpretation: the influence of substituents in 3,4-position on the out-of-plane distortions of the olefinic hydrogen atoms and vicinal torsional interactions in model transition structures.