Investigation of the stereochemistry of the dehydration of the diketide, (3R)-3-hydroxybutyrate to crotonate, in the first chain extension cycle on the aspyrone polyketide synthase in intact cells of Aspergillus melleus
作者:Adam Jacobs、James Staunton
DOI:10.1039/c39950000863
日期:——
When samples of the diketide, (3R)-3-hydroxybutyrate, labelled stereospecifically with deuterium at C-2 in the Re and Si positions, are administered to Aspergillus melleus, and the resulting aspyrone examined by 2H NMR, the (2R-)-[2-2H1]-enantiomer gives a much higher level of incorporation at the expected position which is consistent with a syn elimination mechanism.
Etude par la modélisation moléculaire de la régiosélectivité de l'Ouverture des acides glycidiques par les amines aliphatiques
作者:F. Grosjean、M. Huché、M. Larchevêque、J.J. Legendre、Y. Petit
DOI:10.1016/s0040-4020(01)85509-5
日期:——
A model for glycidic acids opening reaction by ammonia and amines has been suggested from semi-empiric orbital calculations. It provides a way for evaluating the different interactions between the incoming nucleophile and the oxirane substituents. Steric and coulombic interactions of the carboxylate in staggered conformation (cis substitution) has a major influence to rationalize experimental regioselectivity
3S-(1R-Hydroxyethyl)-4R-phenylsulfonylazetidin-2-one derivative was synthesized from L-threonine in an 8-step process including the novel transformation of the oxirane ring to the azetidin-2-one.