Alkynyl-pyridinium ylid complexes of tungsten(0) and chromium(0): synthesis and cascade insertion reactions

Abstract

1,2-dihydropyridine reacts with (1-ethoxy-5-phenylpent-4-ynylidene)pentacarbonyltungsten(0) complex 7 to give the alkynyl pyridinium ylid complex 9 which upon thermolysis leads to an intermediate ketene as the result of the insertions of the triple bond and of CO and which can be trapped by methanol to give the esters 11 and 12 and by dihydrofuran to give the adducts 13 and 14.