Enantioselective benzylic hydroxylation of indan and tetralin with Pseudomonas monteilii TA-5

A set of 22 toluene- and ethylbenzene-degrading strains were screened for the enantioselective benzylic hydroxylation of indan and tetralin, and Pseudomonas monteilii TA-5 was discovered as an active and selective biocatalyst for such hydroxylations. Cells of P. monteilii TA-5 can be easily grown to a high density and demonstrated a specific hydroxylation activity of 24 U/g cdw (cell dry weight). Conditions for the hydroxylation of indan 1a and tetralin 1b with resting cells of this strain were optimized, to give the corresponding (R)-1-indanol 2a and (R)-1-tetralol 2b in 99% ee and 62–67% yields, respectively. No significant product inhibition was observed, and biohydroxylation with cell-free extracts suggested that the responsible hydroxylase is a soluble enzyme depending on either NADH or NADPH. Preparative biohydroxylation was demonstrated with resting cells as biocatalysts, affording (R)-2a in 99% ee and 65% yield, and (R)-2b in 99% ee and in 63% yield, respectively.

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(R)-2,3-Dihydro-1H-inden-1-olC9H10O[α]D22=-35.2 (c 1.05, CHCl3)Ee >99%Source of chirality: enzyme catalysisAbsolute configuration: (R)

(R)-1,2,3,4-Tetrahydronaphthalen-1-olC9H10O[α]D22=-34.9 (c 1.12, CHCl3)Ee >99%Source of chirality: enzyme catalysisAbsolute configuration: (R)