X-ray crystallographic determination of the structure and conformation of new metabolites from microbial hydroxylation by Absidia blakesleeana ATCC 10148

Abstract

The crystal structure and conformation of 10R-hydroxy-1,4,4-trimethyltricyclo[5.4.0.0^3.5]undec-7-en-9-one (II) and 10S-hydroxy-1,4,4-trimethyltricyclo[5.4.0.0^3.5]undec-7-en-9-one (III) have been determined by X-ray diffraction. In both cases the crystals were monoclinic, P2₁,a=12.907 (4),b=7.484(3),c=14.179(4) Å,β=110.65 (3)°,Z=4, (II);a=16.351 (5),b=7.468 (3),c=20.917 (6) Å,β=91.83 (4)°,Z=8 (III). The structure was solved by direct methods, and refined to anR _w value of 0.034 for 2483 (II) and 0.053 for 3810 (III) independent reflections, withI≥3.0σ(I). There were two crystallographically independent molecules in the case ofII and four in the case ofIII. In all independent forms of both compounds the ring substituted by a carbonyl group had the distorted³E sofa conformation; whereas the second one possessed the slightly deformed^7.10B boat conformation. The crystal structures ofII andIII are stabilized by two and four intermolecular hydrogen bonds, respectively.