Application of enzymic Baeyer–Villiger oxidations of 2-substituted cycloalkanones to the total synthesis of (R)-(+)-lipoic acid

Oxidation of ketones 1a–h using a monooxygenase from Pseudomonas putida NCIMB 10007 gave the lactones 2a–h in optically active form: lactone 2h was converted into (R)-(+)-lipoic acid 9.