1. a Department of Organic Chemistry , Technical University of Denmark , Building 201, DK-2800 , Lyngby , Denmark Fax: E-mail:
2. b Danisco Biotechnology , Danisco A/S , Langebrogade 1, PO Box 17, DK-1001 , Copenhagen K , Denmark
3. c Department of Chemistry , Technical University of Denmark , Building 207, DK-2800 , Lyngby , Denmark