Thiol Mediated Free Radical Cyclization of Alkenyl and Alkynyl Isocyanides
摘要:
Thiol-mediated free radical cyclizations of but-3-enyl and but-3-ynyl isocyanides of types 6-8 give new access to 3,5-disubstituted 2-(alkyl- and 2-(arylthio)pyrrolines 11, 12, and 18. When 2-mercaptoethanol is used with the same isocyanides the reaction results in pyroglutamates 16, 17, or 19. These cyclizations involve the formation of a new carbon-carbon bond through intramolecular addition of a carbon-centered thioimidoyl radical to a carbon-carbon multiple bond. Although cyclic products are usually obtained in high yields, in a few cases a competing radical degradation process leading to isothiocyanates was observed. Isocyanide 8a carrying an allyl(phenyl) sulfide moiety isomerizes to 2-(phenylthio)pyrroline 24 in a series of sequential steps.
Synthesis of 3-amino-2,3-dideoxytetrose derivatives
作者:S. David、A. Veyrières
DOI:10.1016/s0008-6215(00)80826-5
日期:1970.5
route, methyl 2-amino-4,4-dimethoxybutyrate (5) was prepared from dl -aspatic acid. Reduction of 5 with lithium aluminium hydride yielded 3-amino-4-hydroxybutyraldehyde dimethylacetal (6 from which the N-acetyl derivative 7 and the diethyl dithioacetal 9 could be prepared. Acid hydrolysis of the (S-isome 7′ of compound 7, prepared from l -aspartic acid, yielded the crystalline 3-acetamido-2,3-dideoxy-