Do enzymes recognise remotely located stereocentres? Highly enantioselective Candida rugosa lipase-catalysed esterification of the 2- to 8-methyldecanoic acids
作者:Erik Hedenström、Ba-Vu Nguyen、Louis A. Silks
DOI:10.1016/s0957-4166(02)00172-6
日期:2002.5
Several racemic methyl decanoic acids have been synthesised and Successfully resolved in esterification with 1-hexadecanol at a(w)=0.8 in cyclohexane using immobilised Candida rugosa lipase (CRL) as the catalyst. The enantiomeric ratios (E=2.8-68) obtained were surprisingly high even when the methyl group was as remotely located as in 8-methyldecanoic acid (E=25). Interestingly, the lipase shows enantiopreference for the S-enantiomer when the methyl group is located on even numbered carbons i.e. for the 2-,4-,6- and 8-methyldecanoic acids and to the R-enantiomer when the methyl group is located on uneven numbered carbons i.e. for the 3-,5- and 7-methyldecanoic acids. (C) 2002 Published by Elsevier Science Ltd.
Aplysillamides A and B, new antimicrobial guanidine alkaloids from the Okinawan marine sponge Psammaplysilla purea
Two new guanidine alkaloids, aplysillamides A (1) and B (2), with antimicrobial activity have been isolated from the Okinawanmarinesponge Psammaplysilla purea and the structures elucidated on the basis of spectroscopic data. The absolute stereochemistry at C-3 of 2 was established as S by synthesis of 2.