Microbial Baeyer-Villiger reaction of bicyclo[3.2.0]heptan-6-ones--a novel approach to sarkomycin A.
Racemic (1 alpha, 2 alpha, 5 alpha)- and (1 beta, 2 alpha, 5 beta)-2- bromobicyclo[3.2.0]heptan-6-one (rac-7, rac-10, respectively), (1 alpha, 2 alpha, 5 beta)- and (1 beta, 2 alpha, 5 beta)-2- benzyloxybicyclo[3.2.0]heptan-6-one (rac-15, rac-13, respectively), (1 beta, 2 alpha, 5 beta)-2-hydroxybicyclo[3.2.0]heptan-6-one (rac-17) and cis-bicyclo[3.2.0]hept-2-en-7-one (rac-18) were subjected to a microbial Baeyer-Villiger reaction by Acinetobacter calcoaceticus NCIB 9871. In each case both regioisomeric lactones were formed (67-93% yield) having always the opposite configuration (20 to > 99 % e.e.). Both the ratio of the regioisomers and the enantiomeric excess proved to be dependent on the type of substitution. Analogously cis-bicyclo[3.2.0]heptan-2,6-dione (rac-1) gave besides other products cyclosarkomycin (1b) (7 % yield, 97 % e.e.). Compound 1b was also obtained from the Baeyer-Villiger product of rac-17 by Swern oxidation (total yield starting from rac-17 9 %, > 98 % e.e.).
Christian Doppler Laboratory for Chiral Compounds, Institute of Organic Chemistry, Graz University of Technology, Austria.
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Königsberger
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Griengl
D016954:Acinetobacter calcoaceticus / Q000378:metabolism*; D001711:Biotransformation; D001643:Bridged Bicyclo Compounds; D002264:Carboxylic Acids / Q000138:chemical synthesis* / Q000737:chemistry; D003517:Cyclopentanes / Q000138:chemical synthesis* / Q000737:chemistry; D007202:Indicators and Reagents; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D015394:Molecular Structure; D013237:Stereoisomerism; D013329:Structure-Activity Relationship
D001643:Bridged Bicyclo Compounds; D002264:Carboxylic Acids; D003517:Cyclopentanes; D007202:Indicators and Reagents; C092083:sarkomycin A