Kinetic resolution of three cyclic quaternary ethyl 1‐amino‐2,3‐dihydro‐1H‐indene‐1‐carboxylates and both 1‐ and 2‐amino‐1,2,3,4‐tetrahydronaphthalene analogues have been studied. Interesterification with butyl butanoate and Candida antarctica lipase B accomplished the task. The enantiomers of all 1‐amino analogues reacted with excellent enantioselectivity (enantiomeric ratio er greater than 200), whereas the 2‐amino analogue was not enantioselective (er = 4). Amino acid enantiomers were finally obtained as their respective hydrochlorides with almost maximum theoretical yields. For the first time, a lipase enzyme was effectively used in the kinetic resolution of cyclic α‐quaternary α‐amino esters.

The kinetic resolution of three dorzolamide intermediates has been studied in the presence of Burkholderia cepacia lipase in organic solvents. All the stereoisomers of 6-methyl-5,6-dihydro-4H-thieno[2,3-b]thiopyran-4-ol were prepared starting from the racemic cis-dihydrothiopyranol intermediate giving first the 4R,6S and 4S,6R enantiomers. Subsequent epimerization and purification of the trans enantiomers by enzymatic acylation or alcoholysis then gave the cis enantio-