Different Reactivities of Alkoxy- and Thiocarbene Complexes of Fischer-Type: Formation of (N-Enamino)ethoxycarbene Complexes and Quinolines, Respectively

Abstract

Alkoxy- and thiocarbene complexes of chromium and tungsten afford different type of products on reaction with (N-aryl)imidoyl chlorides. The (n-butyl)ethoxycarbene complex [(OC)(5)W=C(OEt)n-Bu] and (N-aryl)imidoyl chlorides t-BuClC=NC(6)H(4)R(4) (R(4) = H, OMe) undergo a rearrangement to (N-enamino)ethoxycarbene complexes, whereas quinolines are obtained from the corresponding reaction of (alkyl)thiocarbene complexes [(OC)(5)M=C(SEt)CH(2)R] (M = W, Cr; R = n-Pr, Me) with (N-aryl)imidoyl chlorides R(1)ClC=NC(6)H(2)R(2)R(3)R(4) (R(1) = t-Bu, Ph; R(2), R(3) = H, HC=CH-CH=CH; R(4) = H, OMe, Me) by beta-cyclization.