Stevens rearrangements mediation

A hitherto unknown type of rearrangement of l-(l-alkynyl)cyclopropanols (321) to cyclopent-2-en-l-ones (322) mediated by octacarbonyldicobalt" and hexacarbonyldicobalt" complexes has been described. A possible pathway for the transformation is outlined in Scheme 101. A -proton transfer accompanied by a metal-mediated Stevens rearrangement, which converts a coordinated dimethylsulfane... 

Olah [21] also proposed an ylide mechanism, mediated by a bifunctional acid-base catalyst (e.g., WO3/AI5O3). However, based on isotopic labelling, Olah concludes that the putative ylide would not undergo a Stevens rearrangement, but rather an intermolecular methylation. 

---