Stereochemistry of alkyl 3-substituted 4-halotetrahydro-2-oxo-3-furancarboxylates: 2—1H and13C NMR spectra
摘要:
AbstractThe 1H NMR parameters of methyl 3‐substituted cis‐4‐halotetrahydro‐2‐oxo‐3‐furancarboxylates are reported, with assignments of the ring protons based on solvent‐induced changes in the vicinal trans coupling constants, 3J(H‐4, H‐5). Preferred conformations, ce with a pseudo‐equatorial halogen for the cis isomers and ta with a pseudo‐axial halogen for the trans isomers, have been suggested on comparison of the magnitudes of J(trans) and J(gem) in both series. The 3J(13CH3, H‐4) values measured for methyl cis‐4‐bromotetrahydro‐3‐methyl‐3‐furancarboxylate, methyl trans‐4‐bromotetrahydro‐3‐methyl‐3‐furancarboxylate and trans‐3,4‐dibromodihydro‐3‐methyl‐2(3H)‐furanone have confirmed the stereochemical assignments.
Titanium tetrachloride promoted reaction of silyl ketene acetals with epoxides: a new method for the synthesis of γ-butanolides
作者:Veselin Maslak、Radomir Matović、Radomir N. Saičić
DOI:10.1016/s0040-4039(02)01070-5
日期:2002.7
A new method for the synthesis of γ-butanolides is described. The titaniumtetrachloride promoted reaction of silyl ketene acetals with epoxides, followed by acidic work-up, affords the corresponding butyrolactones in 44–83% yield.
Economical, Green, and Safe Route Towards Substituted Lactones by Anodic Generation of Oxycarbonyl Radicals
作者:Alessia Petti、Matthew C. Leech、Anthony D. Garcia、Iain C. A. Goodall、Adrian P. Dobbs、Kevin Lam
DOI:10.1002/anie.201909922
日期:2019.11.4
A new electrochemical methodology has been developed for the generation of oxycarbonyl radicals under mild and green conditions from readily available hemioxalate salts. Mono- and multi-functionalised γ-butyrolactones were synthesised through exo-cyclisation of these oxycarbonyl radicals with an alkene, followed by the sp3 -sp3 capture of the newly formed carbon-centred radical. The synthesis of functionalised
Analytic and preparative resolution of recemic ?- and ?-lactones by chromatography on cellulose triacetate. Relationship between elution order and absolute configuration
作者:Eric Francotte、Dieter Lohmann
DOI:10.1002/hlca.19870700615
日期:1987.9.23
biologically active substances) have been separated chromatographically on the chiral phase cellulosetriacetate, crystallographic form I (CTAI). For different series of five-membered-ring lactones, relationships have been found between the elutionorder of the enantiomers and their absoluteconfiguration. Preparativeresolutions of γ-Phenyl-γ-butyrolactone (1) and of the Pheromone component 5b have been carried
Disclosed herein are compositions and methods for increasing lifespan, for preventing or treating a disease including an aging-related disorder, for reducing a symptom of aging, and/or boosting an immune system in a mammal. Also disclosed herein are compositions and methods for improving effectiveness of a vaccine in a mammal. The compositions comprise, at least, a therapeutically effective amount of disulfiram and one or more additional ingredients.