Phosphine-Catalyzed Annulation Reactions of 2‑Butynoate and α‑Keto Esters: Synthesis of Cyclopentene Derivatives

We
have developed phosphine-catalyzed annulation reactions for
the synthesis of highly substituted cyclopentene derivatives from
2-alkynoate and α-keto esters. These transformations involve
carbon–carbon
bond cleavage of α-keto esters. Preliminary mechanistic studies
suggest that, in addition to facilitating carbon–carbon bond
formation, the phosphine catalyst plays a role in promoting
methanolysis.