Chiral Bifunctional Ferrocenylphosphine‐Catalyzed Enantioselective Allylic Alkylation of Morita−Baylis−Hillman Carbonates with Pyrazolin‐5‐ones

Abstract

A chiral bifunctional ferrocenylphosphine catalyzed asymmetric allylic alkylation of MoritaÀ BaylisÀ Hillman (MBH) carbonates with pyrazolin-5-ones was developed. The reaction afforded the desired pyrazolone derivatives in moderate to good yields (up to 80%), and with high enantioselectivities (up to 98% ee). Figure 1. Biologically active pyrazolone derivatives. Scheme 1. Pyrazolin-5-one as nucleophilic reagent in asymmetrical transformations.

Recent advances in the applications of pyrazolone derivatives in enantioselective synthesis

“…In this context, Zhong and co-workers developed a bifunctional ferrocenylphosphine C6 catalyzed enantioselective allylic alkylation reaction between pyrazolones 1 and MBH carbonates 15 in 2018 (Scheme 2). 12 This protocol afforded the corresponding pyrazole derivatives 16 in good yields with high enantioselectivities.…”

“…Very recently, based on previous work (Scheme 2), 12 fixing a leaving group on the ortho -position of the MBH carbonate allowed the same catalytic system to support the enantioselective (3 + 3) annulation of pyrazolones 1 and modified MBH carbonates 30 (Scheme 6). 19 The ring-fused pyrazole derivatives 31 , featuring pharmaceutically important quinoline moieties, were then furnished in moderate to high yields with excellent enantioselectivities.…”