2-Methylalkanoic acids resolved by esterification catalysed by lipase from Candida rugosa: Alcohol chain length and enantioselectivity
摘要:
Enantiomerically pure (R)-2-methyldecanoic acid and (S)-2-methyl-1-decanol were prepared in a multi gram scale by esterification reactions catalysed by lipase from Candida rugosa. The enantiomeric ratios (E-values) were determined as a function of the chain length of the alcohol used as the complementary substrate in cyclohexane. In the resolution of 2-methyldecanoic acid the highest value (E = 37 +/- 5) was obtained, when either 1-hexanol, 1-heptanol or 1-octanol were used. In contrast, when resolving 2-methyloctanoic acid, the E-values increased continually with increasing chain length of the alcohol used. 1-Hexadecanol gave the highest value: E > 100. The E-values were determined from the enantiomeric excess (ee) of the product, at, a conversion below 0.4. After two consecutive esterification reactions enantiomerically pure (R)-2-methyldecanoic acid, > 99.8% ee, and after subsequent reduction of the ester produced, (S)-2-methyl-1-decanol, 96.7% ee, were obtained.
Identification of male-specific volatiles from nearctic and neotropical stink bugs (Heteroptera: Pentatomidae)
作者:J. R. Aldrich、J. E. Oliver、W. R. Lusby、J. P. Kochansky、M. Borges
DOI:10.1007/bf02059746
日期:1994.5
Males of the Central American stink bug species, Euschistus obscurus, produce an attractant pheromone composed of a blend of compounds characteristic of North American Euschistus spp. and the South American soybean pest, E. heros. The range of E. obscurus extends into the southern United States, the species is easy to rear, and males produce an exceptionally large quantity of pheromone (>0.5 mug/day/male). These factors made E. obscurus useful for characterizing the novel pheromone components of E. heros without importing this pest species into the United States. Euschistus obscurus males produce methyl (2E,4Z)-decadienoate (61 %) in abundance, which is characteristic of North American species, and methyl 2,6,10-trimethyltridecanoate (27 %), the main male-specific ester of E. heros. The chirality of Euschistus spp. methyl-branched esters, and field activity of synthetic formulations, remain to be determined.
Total Synthesis and Biological Evaluation of Verticipyrone and Analogues
Total synthesis of verticipyrone, a novel NADH-fumarate reductase inhibitor, has been accomplished by a convergent approach using novel "Reverse Julia olefination" method. During total synthetic studies, we also prepared and evaluated several synthetic verticipyrone analogues, some of which exhibited more potent antiparasitic activity than the natural verticipyrone.
Schulte et al., Hoppe-Seyler's Zeitschrift fur Physiologische Chemie, 1951, vol. 288, p. 69,71