The Application of Biocatalysis in the Preparation and Resolution of Morita-Baylis-Hillman Adducts and Their Derivatives.

The Morita-Baylis-Hillman (MBH) reaction affords highly functionalised allylic alcohols containing a new stereogenic centre. These MBH adducts are very versatile and have been transformed into a large range of products, some of which have medicinal potential. Several examples of asymmetric syntheses of MBH adducts have been reported, although a generally applicable method remains to be developed. Biocatalytic approaches for the synthesis and enzymatic kinetic resolution of MBH adducts have been reported, and are discussed in detail in this review. Enzymes able to catalyse the asymmetric MBH reaction have been identified, but selectivity and efficiency have generally been low. Lipases, esterases and nitrile-converting enzymes have all been successfully applied in the resolution of MBH adducts, with excellent selectivity being realised in most cases.

Development of fructose-1,6-bisphosphate aldolase enzyme peptide mimics as biocatalysts in direct asymmetric aldol reactions.

This study describes the design and synthesis of mimetic peptides modelled on the catalytic active site of the fructose-1,6-bisphosphate aldolase (FBPA) enzyme. The synthesized peptides consisting of the turn motifs and catalytic site amino acids of FBPA enzyme were evaluated for catalytic activity in direct asymmetric aldol reactions of ketones and aldehydes. The influence of substrate scope, catalyst loading and solvents including water, on the reaction were also investigated. Nuclear magnetic resonance (NMR) and circular dichroism (CD) were used to determine the secondary structure of the peptides to provide an understanding of the structure-activity relationship. The peptides showed catalytic activity and the aldol products were obtained in low yields (up to 44%), but excellent enantioselectivity (up to 93%) and moderate diastereoselectivity (65 : 35).

A modern and practical laccase-catalysed route suitable for the synthesis of 2-arylbenzimidazoles and 2-arylbenzothiazoles.

Heterocyclic aromatic compounds containing an imine (C[double bond, length as m-dash]N) bond such as benzimidazoles and benzothiazoles are important active pharmaceutical ingredients. The synthesis of 2-aryl-1H-benzimidazoles and 2-arylbenzothiazoles in good to excellent yields was achieved by reacting 2-aminoaromatics with various benzaldehyde derivatives catalysed by the commercial laccases Novoprime and Suberase® at room temperature and in the presence of atmospheric oxygen.