One-Step Convergent Synthesis of the Steroid Ring System via the Coupling of γ,δ-Unsaturated Fischer Carbene Complexes with o-Ethynylbenzaldehyde

Abstract

[reaction: see text]. Simultaneous and stereoselective construction of the steroid B and C rings is observed in a tandem process involving the coupling of o-ethynylbenzaldehyde with 2-alkenylcyclopentylcarbene-chromium complexes.

Group 6 Fischer carbene complexes: “chemical multitalents” for multi-component reactions

“…The intramolecular Diels-Alder version of this tandem reaction has allowed the formation of the steroid ring systems [87] 298 or the tetracyclic frameworks [88] 296 in moderate to good yields, when coupling carbene complexes 295 or 297 with 2-ethynylbenzaldehyde 294 (Scheme 53).…”

Methodology for the Construction of the Bicyclo[4.3.0]nonane Core

“…Of note, the chromium carbene 110 can also be used to simultaneously form B and C rings in steroidal systems when treated with 109. [53] Similar methodology was applied to the synthesis of galliellalactone, which inhibits IL-6 signaling implicated in oncogenic pathways [54].…”

Coarctate cyclization reactions: a primer

“…Initially championed by Herndon [22][23][24] and later by Casey, 25 among others, this methodology has led to a variety of furan derivatives. Transition metal-catalyzed cyclizations of imine-ene-ynes to generate pyrroles are also known, 26 but are much more limited in scope.…”