Transition metal-free [3 + 3] annulation of cyclopropanols with β-enamine esters to assemble nicotinate derivatives

Abstract

An atom-economical synthetic approach for preparing structurally important nicotinates under metal- and additive-free conditions was developed.

Ring‐Opening Functionalization/Cyclization Reactions of Cycloalkanols under Transition‐Metal‐Free Conditions

“…Initially, HCOOH-promoted dehydration of the aromatic-ring cyclobutanols produced cyclobutene inter- Recently, Zhan and co-workers reported a significant method to access structurally valuable nicotinate scaffolds by means of 4-HO-TEMPO mediated [3 + 3] annulation of cyclopropanols with β-enamine esters in the absence of transitional metal catalyst (Scheme 29). [51] The results of large-scale synthetic experiment and oxidant recycling experiment indicated the practicability and sustainability of this method. Control experiments showed that α, β-unsaturated ketone is the key intermediate.…”