A novel reaction of coordinated vinylidenes: coupling with hydrogen sulfide to give a η1-thioaldehyde

Abstract

The Ru^II fragment [(PNP)RuCl₂] assists the coupling of phenylacetylene with H₂S to give 2-phenylethanethial [PNP = CH₃CH₂CH₂N(CH₂CH₂PPh₂)₂] in a reaction that is initiated by alk-1-yne to vinylidene tautomerism at ruthenium, followed by electrophilic attack of H₂S on the vinylidene ligand; 2-phenylethanethial is recovered as either η¹-S-ligand or endo-6-benzyl-1-thiabicyclo[2.2.1]hept-3-ene ligand, and the latter molecule is formed via a stereoselective Diels–Alder reaction between cyclopentadiene and the η¹-2-phenylethanethial complex.