Combination of Rearrangement with Metallic and Organic Catalyses – a Step‐ and Atom‐Economical Approach to α‐Spiroactones and ‐lactams

Abstract

Abstract A general synthetic route to α‐spirolactones and ‐lactams from 2‐diazo‐1,3‐dicarbonyl compounds, (homo)allylic alcohols or amines and acrylic derivatives, involving a single consecutive reaction consisting of a Wolff rearrangement/α‐oxo ketene trapping/cross metathesis/Michael addition sequence is described. During the consecutive reaction optimization, the organocatalytic activity of N , N ‐diaryl‐1,3‐imidazol(in)‐2‐ylidene N‐heterocyclic carbenes (NHCs) in the Michael addition of 1,3‐dicarbonyl compounds was discovered. A conceptually attractive version of the consecutive reaction was then developed, involving the Grubbs–Hoveyda ruthenium‐based precatalyst containing the SIMes [1,3‐bis(2,4,6‐trimethylphenyl)imidazolin‐2‐ylidene] NHC ligand as the source of both the organometallic catalyst of the cross metathesis and the organic catalyst of the intramolecular Michael addition.