A Highly Diastereoselective and Enantioselective Synthesis of Polysubstituted Pyrrolidines via an Organocatalytic Dynamic Kinetic Resolution Cascade
摘要:
Highly functionalized pyrrolidine and piperidine analogues, with up to three stereogenic centers, were synthesized in good yield (50 - 95%), excellent dr (single isomer), and high ee (>90%) using a Cinchona alkaloid-derived carbamate organocatalyst. High stereoselective synergy was achieved by combining a reversible aza-Henry reaction with a dynamic kinetic resolution (DKR)-driven aza-Michael cyclization. Whereas both reactions proceed with moderate enantioselectivities (50-60% for each step), high enantioselectivities are obtained for the overall products devoid of dr sacrifice.
The first enantioselective aza-Friedel-Crafts reaction between pyrroles and enamides has been achieved by using novel H8-BINOL type imidodiphosphoric acid catalyst. This methodology was also applied to the highly enantioselective aza-Friedel-Crafts...
cyclopropenes to imines by leveraging the synergy between photoredox and asymmetric cobalt catalysis. This protocol facilitated the synthesis of a series of chiral functionalized cyclopropanes with high yield, enantioselectivity, and diastereoselectivity (44 examples, up to 93% yield and >99% ee). A possible reaction mechanism involving cyclopropene desymmetrization by Co–H species and imine addition by