Differences in the Regio- and Stereoselectivity of the Microbial Hydroxylation of a Derivatized Cyclopentanecarboxylic Acid by Employing Various Mucorales Strains

Michaela Kreiner1, Gerhart Braunegg1, Anna de Raadt Herfried Griengl2, Peter Plachota2, Hansjörg Weber2

Institute of Biotechnology, Technical University of Graz, Petersgasse 12, 8010 Graz, Austria

2Institute of Organic Chemistry, Technical University of Graz, Stremayrgasse 16, 8010 Graz, Austria

Article history:

Received December 19, 1996
Accepted March 21, 1997

Key words:

biohydroxylation, mucorales, stereochemistry


Mucorales strains Absidia glauca, Mortierella alpina, Mucor plumbeus, Phycomyces blakesleeanus, Rhizopus oryzae, and Syncephalastrum racemosum were found to be efficient biocatalysts for the biotransformation of derivatized cyclopentanecarboxylic acid into hydroxy and oxo derivatives. Cyclopentanecarboxylic acid was protected against microbial degradation by chemical transformation into 2-cyclopentybenzoxazole 1. The biotransformation yielded 3-(benzoxazol-2-yl)cyclopentan-l-ol 3 as the main product. 2-(Benzoxazol-2yl)cyclopentan-l-ol 2 and 3-(benzoxazol-2-yl)cyclopentan-l-one 4 were delected as by-products.
The enantiomeric compositions and optical purities of the main products were determined in order to compare interspecific differences in the regio- and stereoselectivity of the fungal species. The main product 3 produced by M. plumbeus, R. oryzae, and S. racemosum was predominantly the (1S,3S)-enantiomer, whilst that formed by A. glauca, M. alpina, and P. blakesleeanus was predominantly the (lR,3R)-enantiomer. The results indicate that although related fungi may exhibit similar product spectra, there are differences in regio- and stereoselectivity that are species dependent.