A sustainable enzymatic strategy for the preparation of amides by using Candida antarctica lipase B as the biocatalyst and cyclopentyl methyl ether as a green and safe solvent was devised. The method is simple and efficient and it produces amides with excellent conversions and yields without the need for intensive purification steps. The scope of the reaction was extended to the preparation of 28 diverse amides using four different free carboxylic acids and seven primary and secondary amines, including cyclic amines. This enzymatic methodology has the potential to become a green and industrially reliable process for direct amide synthesis.

This report reviews the most important lipase-catalyzed strategies for the preparation of pharmaceutically and chemically important tetrahydroisoquinoline and tetrahydro-β-carboline enantiomers through O-acylation of the primary hydroxy group, N-acylation of the secondary amino group, and COOEt hydrolysis of the corresponding racemic compounds with simple molecular structure, which have been reported during the last decade. A brief introduction describes the importance and synthesis of tetrahydroisoquinoline and tetrahydro-β-carboline derivatives, and it formulates the objectives of this compilation. The strategies are presented in chronological order, classified according to function of the reaction type, as kinetic and dynamic kinetic resolutions, in the main text. These reactions result in the desired products with excellent ee values. The pharmacological importance of the products together with their synthesis is given in the main text. The enzymatic hydrolysis of the hydrochloride salts as racemates of the starting amino carboxylic esters furnished the desired enantiomeric amino carboxylic acids quantitatively. The enzymatic reactions, performed in tBuOMe or H₂O as usable solvents, and the transformations carried out in a continuous-flow system, indicate clear advantages, including atom economy, reproducibility, safer solvents, short reaction time, rapid heating and compression vs. shaker reactions. These features are highlighted in the main text.

This article provides a review of the paramount lipase-catalyzed strategies employed in the preparation of (2R,3S)-3-amino-2-hydroxy-3-phenylpropionic acid, several of its derivatives, and precursor 2-azetidinones through β-lactam ring opening, OAc hydrolysis, COOEt hydrolysis, O-acylation, and sequential kinetic resolution through a two-step cascade reaction. It involves OAc hydrolysis followed by β-lactam ring opening and β-lactam ring opening followed by hydroxymethyl group degradation of the corresponding racemic compounds, reported over the last 15 years. A brief introduction describes the pharmaceutical and chemical importance of the Taxol molecule as well as various synthetic methods involving its side chain and it delineates the key objectives of this mini-review. The strategies are classified on the basis of reaction types and are presented in chronological order, discussing kinetic and sequential kinetic resolutions in the main text. These reactions yield the intended products, exhibiting excellent enantiomeric excess values.