Pd-Catalyzed Formal [2 + 2]-Retrocyclization of Cyclobutanols via 2-Fold Csp³–Csp³ Bond Cleavage

Abstract

In this work, we describe the unexpected 2-fold Csp 3 −Csp 3 bond cleavage suffered by cyclobutanols in the presence of a catalytic amount of Pd(OAc) 2 and promoted by the bulky biaryl JohnPhos ligand. Overall, the sequential cleavage of a strained and an unstrained Csp 3 −Csp 3 bond leads to the formal [2 + 2]-retrocyclization products, namely, styrene and acetophenone derivatives. This procedure might enable the use of cyclobutanols as masked acetyl groups, resisting harsh conditions in organic synthesis.

Pd-Catalyzed Ring-Opening Polymerization of Cyclobutanols through C(sp3)–C(sp3) Bond Cleavage

“…Interestingly, a minor polymeric series showed a mass corresponding to a Me­(CO)-C 6 H 4 end-group (Scheme f). We have previously observed that cyclobutanol reagents can undergo a Pd-catalyzed 2-fold C­(sp 3 )–C­(sp 3 ) bond cleavage, especially when using JohnPhos as a ligand . This process provokes the formal [2 + 2]-retrocyclization of the cyclobutanol fragment, giving the corresponding alkene and acetophenone.…”