Lipase-catalyzed kinetic resolution of (RS)-hydroxy tellurides
作者:Alcindo A. Dos Santos、Carlos E. Da Costa、Jefferson L. Princival、João V. Comasseto
DOI:10.1016/j.tetasy.2006.07.024
日期:2006.9
The enzymatic resolution of racemic mixtures of hydroxy tellurides with a range of lipases has been investigated. Lipase-B from Candida antarctica (CALB) gave the best conversions, providing both enantiomers with high enantiomeric purity. A comparative study of the effect of solvent and substrate on the enzymatic kinetic resolution was performed. (c) 2006 Elsevier Ltd. All rights reserved.
γ-Butyltelluro-2-butanol: a route to reactive 1,4-dianion intermediates
作者:Jefferson L. Princival、Simone M.G. de Barros、João V. Comasseto、Alcindo A. Dos Santos
DOI:10.1016/j.tetlet.2005.05.002
日期:2005.6
gamma-Butyltelluro-2-butanol was reacted with 2 equiv of n-butyllithium. Both tellurium/lithium exchange and the proton abstraction reactions took place in a single step and the lithium dianion intermediate efficiently reacted with aldehydes and ketones, producing the corresponding diols. (c) 2005 Elsevier Ltd. All rights reserved.
Tellurium in organic synthesis: the enantioselective synthesis of the pheromone blend components of Mayetiola destructor, Drosophila mulleri and Contarinia pisi
作者:Renan S. Ferrarini、João V. Comasseto、Alcindo A. Dos Santos
DOI:10.1016/j.tetasy.2009.08.003
日期:2009.9
The components of the pheromone blend of Mayetiola destructor, Drosophila mulleri, and Contarinia pisi were synthesized in high enantiomeric excess (99% ee) from a common enantiopure dianion prepared from an enantiopure hydroxytelluride. (C) 2009 Elsevier Ltd. All rights reserved.
Tellurium/lithium exchange reactions in the synthesis of spiroketals and 1,6-dioxygenated systems
作者:Alcindo A. Dos Santos、Jefferson L. Princival、João V. Comasseto、Simone M.G. de Barros、José E. Brainer Neto
DOI:10.1016/j.tet.2007.03.178
日期:2007.6
O-dianions have been generated through concomitant acid/base and tellurium/lithium exchange reactions. The di-lithium salts were transmetallated with cerium chloride to the corresponding di-cerium salts and subsequently reacted with lactones and carboxylic acid anhydrides to yield the respective spiroketals. The di-lithium entities were also converted into the corresponding cyanocuprates that add in
Functionalized organozincates and organocuprates derived from γ-hydroxytellurides in the preparation of 1,4-hydroxyketones
作者:Jefferson L. Princival、Alcindo A. Dos Santos、João V. Comasseto
DOI:10.1016/j.tetlet.2009.08.097
日期:2009.11
A C-O-dianionic zincate was generated by a Te/Li exchange reaction of an alkyltelluride, followed by Li/Zn transmetallation and reaction with methyllithium. The reaction between the enantiomerically pure (99% ee) (R)-dianionic zincate and benzoyl chloride led to 3-hydroxy-1-phenyl pentanone with total retention of the carbon configuration (99% ee). Similar results were obtained using the corresponding Lipshutz cyanocuprates. (C) 2009 Elsevier Ltd. All rights reserved.