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Enzyme-Catalyzed Stereoselective Synthesis of Two Novel Carbasugar Derivatives
Date
2010-01-01
Author
Gumus, Aysegul
Tanyeli, Cihangir
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Enzymatic resolution of racemic 1,4,5,6-tetrachloro-2-(hydroxymethyl)-7,7-dimethoxybicyclo[2.2.1]hept-5-ene (rac-1) using various lipases in vinyl acetate as acetyl source was studied. The obtained enantiomerically enriched (+)-(1,4,5,6-tetrachloro-7,7-dimethoxybicyclo[2.2.1]hept-5-en-2-yl)methyl acetate ((+)-2; 94% ee), upon treatment with Na in liquid NH3, followed by Amberlyst-15 resin in acetone, provided (-)-5-(hydroxymethyl)bicyclo[2.2.1]hept-2-en-7-one ((-)-7), which is a valuable precursor for the synthesis of carbasugar derivatives. Subsequent Baeyer-Villiger oxidation afforded a nonseparable mixture of bicyclic lactones, which was subjected to LiAlH4 reduction and then acetylation. The resultant compounds (-)-11 and (+)-12 were submitted to a cis-hydroxylation reaction, followed by acetylation, to afford the novel carbasugar derivatives (1S,2R,3S,4S,5S)-4,5-bis(acetoxymethyl)cyclo-hexane-1,2,3-triyl triacetate ((-)-(13)) and (1R,3R,4R,6R)-4,6-bis(acetoxymethyl)cyclohexane-1,2,3-triyl triacetate ((-)(14)), respectively, with pseudo-C-2-symmetric configuration. The absolute configuration of enantiomerically enriched unreacted alcohol (-)-1 (68% ee) was determined by X-ray single-crystal analysis by anchoring optically pure (R)-1-phenylethanamine. Based on the configurational correlation between (-)-1 and (+)-2, the absolute configuration of (+)-2 was determined as (1R,2R,4S).
Subject Keywords
Hexachloronorbornadiene Dderivatives
,
Norbornyl route
,
Resolution
,
Lipase
,
Fragmentation
,
Sugars
,
Acid
URI
https://hdl.handle.net/11511/55525
Journal
HELVETICA CHIMICA ACTA
Collections
Department of Chemistry, Article
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A. Gumus and C. Tanyeli, “Enzyme-Catalyzed Stereoselective Synthesis of Two Novel Carbasugar Derivatives,”
HELVETICA CHIMICA ACTA
, pp. 1882–1893, 2010, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/55525.