Acylative Kinetic Resolution of Racemic 2,2‐Dimethyl‐Substituted Nitroaldol (Henry) Adducts Using a Chiral Guanidine Catalyst: (R)‐(+)‐N‐Methylbenzoguanidine ((R)‐NMBG)

Abstract

Non‐enzymatic acylative kinetic resolution of racemic 2,2‐dimethyl‐substituted nitroaldol (Henry) adducts was achieved using cyclohexanecarboxylic anhydride in the presence of chiral guanidine catalyst. The systematic evaluation of the substituents on the aromatic rings of the substrates were conducted to clarify the influence of the substituents. The reaction was smoothly proceeded with moderate to good s‐values, regardless of the kinds of the substituents. Based on the absolute configuration of the resulted product, the transition state of the reaction was predicted, and it was important the interaction between the nitro group on the substrate and the cation face of the acyl‐guanidium intermediate to determine the direction of the substrate.