Stereoselective cyclopropanation of enamides via C–C bond cleavage of cyclopropenes

Abstract

This work describes a straightforward protocol for the stereoselective synthesis of vinylcyclopropylamides in high E/Z and syn/anti ratios by cyclopropanation of N-tosyl substituted enamides with cyclopropenes in the presence of...

Reassembly of Unsaturated C–C Bonds by a Cutting/Insertion Cascade

“…Although the mechanism responsible for controlling the E/Z selectivity remains unclear, the tosyl group of the enaminone is believed to play an essential role in this transformation. This strategy was further applied in cyclopropanations of tosyl-substituted indoles 27 and enamides 28 with vinyl carbenes formed by ring opening of unsymmetrical cyclopropenes; these reactions showed good to excellent E/Z selectivities.…”

Phenol-mediated decarboxylative proton transfer of γ-methylidene-δ-valerolactones: an approach towards (E)-2,4-pentadienoates

“…Elimination reactions 8 a and olefination reactions 8 b have been widely employed, but they are frequently associated with the problems of uncontrolled generation of E and Z isomers, which need rigorous purification. In the past decades, to realize the stereoselective synthesis of substituted 1,3-dienes, a variety of strategies have been developed, 9 including vinyl C–H bond activation, 9 d cross-coupling reactions, 10 ene-yne metathesis, 11 functionalization of alkynes 12 or 1,3-diynes, 13 isomerization, 14 Kumada vinylation 15 and aerobic dehydrogenation. 16 Despite the effectiveness of the aforementioned methods, developing a direct, highly stereoselective approach towards the synthesis of polysubstituted 1,3-conjugated dienes remains elusive and is highly desirable.…”