Toluene- and naphthalene-dioxygenase-catalysed sulfoxidation of nine disubstituted methylphenyl sulfides, using whole cells of Pseudomonas putida, consistently gave the corresponding enantioenriched sulfoxides. Using the P. putida UV4 mutant strain, and these substrates, differing proportions of the corresponding cis-dihydrodiol sulfides were also isolated. Evidence was found for the concomitant dioxygenase-catalysed cis-dihydroxylation and sulfoxidation of methyl para-tolyl sulfide. A simultaneous stereoselective reductase-catalysed deoxygenation of (S)-methyl para-tolyl sulfoxide, led to an increase in the proportion of the corresponding cis-dihydrodiol sulfide. The enantiopurity values and absolute configurations of the corresponding cis-dihydrodiol metabolites from methyl ortho- and para-substituted phenyl sulfides were determined by different methods, including chemoenzymatic syntheses from the cis-dihydrodiol metabolites of para-substituted iodobenzenes. Further evidence was provided to support the validity of an empirical model to predict, (i) the stereochemistry of cis-dihydroxylation of para-substituted benzene substrates, and (ii) the regiochemistry of cis-dihydroxylation reactions of ortho-substituted benzenes, each using toluene dioxygenase as biocatalyst.
Dioxygenase-catalysed trioxygenation of alkyl phenyl sulfides and alkyl benzenes yields enantiopure cis-dihydrodiol sulfoxides and triols respectively; naphthalene cis-dihydrodiol dehydrogenase-catalysed aromatisation of these diastereoisomers gives enantiopure catechols of either configuration.
Enzymatic and Chemoenzymatic Synthesis and StereochemicalAssignment of cis-Dihydrodiol Derivatives of Monosubstituted Benzenes.-The title compounds (V) and (III) are prepared via enzymatic oxidation of benzene derivatives (IV) or Pd-catalyzed cross-coupling of enantiopure cis-diols (I). The enantiopurities and absolute configuration of (V) are determined by spectroscopic and X-ray analyses of the bis-MTPA esters of the cycloadducts (VII). -(BOYD, D. R.; SHARMA, N. D.; BYRNE, B.; HAND, M. V.; MALONE, J. F.; SHELDRAKE, G. N.; BLACKER, J.; DALTON, H.; J. Chem. Soc., Perkin Trans. 1 [old] (1998) 12, 1935-1943 Sch. Chem., Queen's Univ., Belfast BT9 5AG, UK; EN)
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