The cycloaddition reactions of nickel(II) beta-vinyl-meso-tetraphenylp
orphyrins with tetracyanoethylene (TCNE) in chloroform, afford [2+2] a
dducts containing a cyclobutane ring and [4+2] adducts. The [2+2] addu
cts can also be produced by rearrangement of the [4+2] chlorins. Copyr
ight (C) 1996 Elsevier Science Ltd