tailieunhanh - Using Vietnamese fresh carrot as a biocatalyst in organic synthesis

Fresh root of Vietnamese carrot (Daucus carota L.) has been employed as a biocatalyst in the asymmetric reduction of prochiral ketones and the enantioselective hydrolysis of racemic esters. In the previous reaction, (S)-alcohols were formed in quantitative yield with highly enantiomeric purity (ee > 93%). However in the latter, this biocatalyst presented a poor enantioselectivity (ee < 50%). Besides, the selectively reducing capability of carrot on a conjugated aldehyde and a racemic mixture of aldehyde was also investigated. | Journal of Chemistry Vol. 44 6 P. 772 - 776 2006 USING VIETNAMESE FRESH CARROT AS A BIOCATALyST IN ORGANIC SyNTHESIS Received 17 December 2005 HIEN QUANG DO1 THACH NGQC LE1 ANH Huu TRAN2 PHUONG THI MINH HA1 AND THAO THI PHUONG NGUYEN1 1 Department of Organic Chemistry Faculty of Chemistry University of Natural Sciences 2Department of Chemistry Memorial University of Newfoundland Canada SUMMARY Fresh root of Vietnamese carrot Daucus carota L. has been employed as a biocatalyst in the asymmetric reduction of prochiral ketones and the enantioselective hydrolysis of racemic esters. In the previous reaction S -alcohols were formed in quantitative yield with highly enantiomeric purity ee 93 . However in the latter this biocatalyst presented a poor enantioselectivity ee 50 . Besides the selectively reducing capability of carrot on a conjugated aldehyde and a racemic mixture of aldehyde was also investigated. I - INTRODUCTION Chiral alcohols have been played important roles in organic synthesis especially in asymmetric synthesis for the production of fine chemicals pharmaceuticals agrochemicals flavours and materials 1 . Generally these optically active alcohols can be obtained by asymmetric synthesis and or racemic resolution using chiral chemical catalysts. However these traditional methods are disadvantageously recognized as their high cost low selectivity unfriendly environment etc. Therefore an increasing attention has been paid to biocatalysts because of their great advantages such as very high selectivity benign to environment cheap and easy for handling in some cases. Numerous biocatalysts have been widely and successfully employed such as baker s yeast in asymmetric reduction lipases in racemic resolution 1 2 and higher plants used in forms of cell cultures or fresh organs of plants 3 - 8 . Outstanding from plant biocatalysts carrot has recently gained a remarkable attention of many chemists to study thoroughly about this useful catalyst. Most reports focused on .

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