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The use of whole cells of micro-organisms to bring about the biotransformation of an organic compound offers a number of advantages, but problems caused by enzymatic promiscuity may be encountered upon with substrates bearing more than one functional group. A one-pot screening method, in which whole fungal cells were incubated with a mixture of 4-methylcyclohexanone 1 and phenyl methyl sulfide 2 , has been employed to determine the chemoselectivity of various biocatalysts. The hyphomycetes, Aspergillus terreus CCT 3320 and A. terreus URM 3571, catalysed the oxidation of 2 accompanied by the reduction of 1 to 4-methylcyclohexanol 1a and, for strain A. terreus CCT 3320, the Baeyer-Villiger oxidation of 1 . The Basidiomycetes, Trametes versicolor CCB 202, Pycnoporus sanguineus CCB 501 and Trichaptum byssogenum CCB 203, catalysed the oxidation of 2 and the reduction 1 , but no Baeyer–Villiger reaction products were detected. In contrast, Trametes rigida CCB 285 catalysed the biotransformation of 1 to 1a , exclusively, in the absence of any detectable sulfide oxidation reactions. The chemoselective reduction of (±)-2-(phenylthio)cyclohexanone 3 by T. rigida CCB 285 afforded exclusively the (+)- cis -(1 R , 2 S) and (+)- trans -(1 S ,2 S ) diastereoisomers of 2-(phenylthio)cyclohexan-1-ol 3a in moderate yields (13% and 27%, respectively) and high enantiomeric excesses (>98%). Chemoselective screening for the reduction of a ketone and/or the oxidation of a sulfide group in one pot by whole cells of micro-organisms represents an attractive technique with applications in the development of synthesis of complex molecule bearing different functional groups.

Edible tuberous roots of the species Arracacia xanthorrhiza and Beta vulgaris together with the associated microorganism, Candida guilliermondii, biocatalysed the reduction of several nitro-aromatic substrates to yield the respective amines, and the subsequent acetylation of the amine products to the corresponding acetamides. The enzymatic formation of acetamides has rarely been reported in association with the bioreduction of nitro groups. The biotransformation reactions catalysed by roots of A. xanthorrhiza, B. vulgaris and C. guilliermondii occurred independently of the locality of origin of the plant material. Consortiums of microorganism were isolated and identified as C. guilliermondii from A. xanthorrhiza and B. vulgaris roots. The C. guillermondii was able to catalyse the biotransformation of nitrobenzene into aniline. The acetanilide was not obtained by C. guilliermondii. The results demonstrate that roots of A. xanthorrhiza may be employed in the synthesis of amines and acetamides under very mild conditions. Moreover, the tuberous roots of these plants may have application in the bioremediation of nitro-aromatic compounds.

Mannich base derivatives 1–3 were biotransformed through tandem enzymatic reactions by using several microorganisms isolated from Brazilian biomes. The hydrochlorides 1 and 3 produced propiophenone 1a, α,β-unsatured ketone 2c and alcohol (S)-1b (yield 40%, e.e. 81%, Aspergillus terreus). The hydrochloride 2 underwent the Baeyer–Villiger oxidation producing exclusively para-methoxy-phenol by A. terreus and A. niger. The propiophenone 1a was reduced to their corresponding enantiomerically enriched phenylpropanol (S)-1b (yield 65%, e.e. 81%, A. terreus). The para-methoxy-propiophenone 2a afforded Baeyer–Villiger reaction hydrolyzed product, the para-methoxy-phenol (yield 80%, A. terreus). The racemic phenylpropanols 1b,2b were resolved by lipase-catalyzed kinetic resolution (Novozym 435) affording (S)-alcohols 1b,2b and (R)-acetates 1d,2d in high enantiomeric excesses (up to 99%) and good yields (40–45%). We screened new microorganisms in biotransformation of Mannich bases, propiophenones and applied enzymatic resolution of phenylpropanols by Candida antarctica lipase.