Naphthalene-dioxygenase-catalysed cis-dihydroxylation of azaarene derivatives: Part 1: 2-Pyridones and 2-quinolones

The scope of the biotransformation of 2-pyridone- and 2-quinolone-derived compounds by recombinant whole-cells of E. coli JM109(DE3)(pDTG141) expressing the naphthalene-dioxygenase system from Pseudomonas sp. NCIB 9816-4 was explored, using a series of N- and C-substituted derivatives. Among them, only the N-methyl substituted compounds were good substrates for a regio- and stereoselective dihydroxylation reaction leading to cis-dihydroxydihydro pyridone derivatives, corresponding to the general pattern expected for this enzyme. In the absence of dihydroxylation reactions, N-dealkylations and monohydroxylations on external methyl groups were observed.