Regio‐, Diastereo‐, and Enantioselective Organocatalytic Addition of 4‐Substituted Pyrazolones to Isatin‐Derived Nitroalkenes

Abstract

Hydroquinine 2,5‐diphenyl‐4,6‐pyrimidinediyl diether [(DHQ)2Pyr] catalyzed the regio‐, diastereo‐, and enantioselective addition of 4‐substituted pyrazolones to isatin‐derived nitroalkenes, providing a variety of chiral alkenylpyrazolone adducts containing a tetrasubstituted stereocenter bearing an oxindole moiety with excellent yields, regioselectivity, and diastereoselectivity, as well as a moderate enantioselectivity (up to 98 % yield, > 20:1 E/Z ratio dr and 78 % ee). The reaction harnesses a nitroalkene as an alkenylating agent through a Nucleophilic Vinylic Substitution (SNV) reaction.