Efficient syntheses of the eight stereoisomers of muscarine have been accomplished by dehydrogenase-catalyzed reduction of iodo ketones (+/-)-3a and (+/-)-3b. 3-alpha,20-beta-Hydroxysteroid dehydrogenase from Streptomyces hydrogenans exhibited high enantiomeric and diastereotopic selectivity for (+/-)-3a, yielding an equimolar mixture of iodo alcohol (-)-4 (2S,4S,5S) (96\% ee) and iodo ketone (+)-3a (2R,5R) (96\% ee) which was reduced by sodium borohydride to a mixture of (+)-4 and (+)-5. 3-beta,17-beta-Hydroxysteroid dehydrogenase from Pseudomonas testosteroni reduced (+/-)-3b with high diastereotopic selectivity to give an equimolar mixture of iodo alcohols (+)-6 (2R,4S,5S) (> 99\% ee) and (-)-7 (2S,4S,5R) (81\% ee). Synthesis of the remaining iodo alcohols {[(-)-5, (-)-6, and (+)-7] was achieved by applying the Mitsunobu procedure to (-)-4, (-)-7, and (+)-6. The enantiomeric excess of intermediates 4-7 was determined by HPLC analysis of the (R)-(+)-MTPA esters. The chiral iodo alcohols 4-7 were then transformed into the final derivatives by conventional chemical manipulations.}
CHEMOENZYMATIC SYNTHESIS OF THE 8 STEREOISOMERIC MUSCARINES / M. De Amici, C. De Micheli, G. Molteni, D. Pitré, G. Carrea, S. Riva, S. Spezia, L. Zetta. - In: JOURNAL OF ORGANIC CHEMISTRY. - ISSN 0022-3263. - 56:1(1991), pp. 67-72. [10.1021/jo00001a015]
CHEMOENZYMATIC SYNTHESIS OF THE 8 STEREOISOMERIC MUSCARINES
M. De Amici;C. De Micheli;
1991
Abstract
Efficient syntheses of the eight stereoisomers of muscarine have been accomplished by dehydrogenase-catalyzed reduction of iodo ketones (+/-)-3a and (+/-)-3b. 3-alpha,20-beta-Hydroxysteroid dehydrogenase from Streptomyces hydrogenans exhibited high enantiomeric and diastereotopic selectivity for (+/-)-3a, yielding an equimolar mixture of iodo alcohol (-)-4 (2S,4S,5S) (96\% ee) and iodo ketone (+)-3a (2R,5R) (96\% ee) which was reduced by sodium borohydride to a mixture of (+)-4 and (+)-5. 3-beta,17-beta-Hydroxysteroid dehydrogenase from Pseudomonas testosteroni reduced (+/-)-3b with high diastereotopic selectivity to give an equimolar mixture of iodo alcohols (+)-6 (2R,4S,5S) (> 99\% ee) and (-)-7 (2S,4S,5R) (81\% ee). Synthesis of the remaining iodo alcohols {[(-)-5, (-)-6, and (+)-7] was achieved by applying the Mitsunobu procedure to (-)-4, (-)-7, and (+)-6. The enantiomeric excess of intermediates 4-7 was determined by HPLC analysis of the (R)-(+)-MTPA esters. The chiral iodo alcohols 4-7 were then transformed into the final derivatives by conventional chemical manipulations.}Pubblicazioni consigliate
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