Recent Experimental and Computational Studies of the Mechanisms of Enantioselection in Asymmetric Catalytic Reactions

Abstract

Minireview describes most recent mechanistic studies of the synthetically or theoretically important catalytic asymmetric reactions. Contrary to the commonly accepted view of competition between two almost identical catalytic pathways leading to the opposite enantiomers of the product, in most cases it was essential to analyze numerous mechanistic possibilities and competition of structurally dissimilar catalytic pathways.

A Quantification of the Soai Reaction

“…Among them, they described the so‐called square‐macrocycle‐square (SMS) tetramer that holds two trigonal Zn centers that could either play the role of the catalyst or polymerize to ladder‐shaped oligomeric fragments . To quantify the sophisticated equilibria that occur in the Soai reaction, a combined DFT computational and NMR spectroscopy experimental study has been performed . The tetramers formed by the dimerization of the homochiral square dimers adopt a SMS‐like conformation with orthogonal pyrimidinyl rings.…”

“…[20] To quantify the sophisticated equilibria that occur in the Soai reaction, ac ombined DFT computational and NMR spectroscopy experimental study has been performed. [21][22][23] The tetramers formed by the dimerization of the homochiral square dimers adopt aS MS-like conformation with orthogonalp yrimidinyl rings. The homochiral tetramer forms an ideal chiral cavity for the enantioselective alkylation of the aldehyde, whereas the heterochiraltetramer is practically excluded from the catalytic flow.F inally,t hese authors call attention to the fact that ee amplification requires an adjusted reversibility of the different reactions teps.…”