Separation of (S)-(−)-3-Methyl-2-pyrrolidinone as an Inclusion Complex with (R)-(+)-4,4′,6,6′-Tetrachloro-2,2′-bis(hydroxydiphenylmethyl)-1,1′-biphenyl Host and its X-ray Structural Study

Abstract

By inclusion complexation with the chiral host compound (R)-(+)-4,4′,6,6′-tetrachloro-2,2′-bis(hydroxydiphenylmethyl)-1,1′-biphenyl, racemic 3-methyl-2-pyrrolidinone was resolved and its (S)-(−)-enantiomer was isolated as a 1:1 inclusion complex, which crystallises in the orthorhombic crystal system in the space group P212121 (a = 14.1163(2) A, b = 14.7140(3) A, c = 17.2025(3) A). By the inclusion complexation, the keto–enol equilibrium of the guest was frozen and the keto-form was isolated in a pure form. By X-ray structural study of the complex, the guest molecule included was elucidated to be the keto-form and its absolute configuration was determined to be (S). By inclusion complexation with (R)-(+)-4,4′,6,6′-tetrachloro-2,2′-bis (hydroxydiphenylmethyl)-biphenyl, racemic 3-methyl-2-pyrrolidinone was resolved and its (S)-(−)-enantiomer isolated and in addition the keto–enol equilibrium of the guest was frozen and the keto-form isolated.