Synthesis of aromatic and heteroaromatic thioaldehydes, aryl-thioenals, and -thiodienals as their η1; complexes with pentacarbonyltungsten(0) by the reaction of aldimines and a new reagent, [PPh4][W(CO)5SH]

Abstract

A new reagent, [PPh₄][W(CO)₅SH]1 for the synthesis of pentacarbonyltungsten(0) complexes of thioaldehydes has been synthesised from [PPh₄]SH and [W(CO)₅(C₄H₈O)]. The latter was formed conveniently by a nonphotochemical process. Treatment of each imine 2 with [PPh₄][W(CO)₅SH]1 in the presence of equimolar mixture of BF₃·OEt₂ and McCO₂H (2 equiv.) gave complexes of the thiobenzaldehydes 3a–j, thionaphthaldehydes 4a–b, thioanthraldehydes 5a–b, 5-methyl-2-thioformylfuran 6, 2-thioformylthiophenes 7a–c, 4-substituted thiocinnamaldehydes 8a–c, and 4-substituted thiocinnamylideneacetaldehydes 9a–c with pentacarbonyltungsten(0) in high yields. NMR studies revealed that the above exist as η¹ complexes.