RESUMO
[reaction: see text]. An approach to the asymmetric intramolecular meta photocycloaddition of phenoxyalkenes is described. The beta-cyclodextrin complexes of several phenoxyalkenes have been synthesized and irradiated in the solid phase. The effect of the CD-hosting on the regio- and enantioselectivity is discussed. Values of ee up to 17% were obtained.
Assuntos
Alcenos/química , Ciclodextrinas/química , Fotoquímica/métodos , Cromatografia Líquida de Alta Pressão , Espectroscopia de Ressonância Magnética , Modelos QuímicosRESUMO
Indanol intermediates 5, prepared via Michael addition of 1-indanone beta-ketoester and acrylonitrile followed by reduction or Grignard reaction of the ketone group, were submitted to intramolecular Ritter reaction using various acid reaction conditions to produce tricyclic lactams 4. This cis-fused hexahydro-4aH-indeno[1,2-b]pyridine ring system, substituted at both angular positions 4a and 9b, provides access to constrained analogues of non-peptide NK(1)-antagonists with monocyclic piperidine structure.
Assuntos
Compostos de Bifenilo/química , Antagonistas dos Receptores de Neurocinina-1 , Piperidinas/química , Piridinas/síntese química , Substância P/antagonistas & inibidores , Cromatografia em Camada Fina , Cristalografia por Raios X , Ciclização , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Piridinas/química , Receptores da Neurocinina-1/química , EstereoisomerismoRESUMO
Two new triterpenoid saponins isolated from the root bark of Heinsia crinata were characterized as heinsiagenin A-3 beta-O-(beta-D-glucopyranosyl-(1-->2)-beta-D-glucopyranosyl- (1-->6)-[alpha-L-rhamnopyranosyl-(1-->2)]-beta-D-glucopyranosyl-(1-->2)- beta-D-glucopyranoside) and heinsiagenin A-3 beta-O-(alpha-L-rhamnopyranosyl-(1-->2)-beta-D- glucopyranosyl-(1-->2)-beta-D-glucopyranoside). The structures were deduced mainly from a combination of 1- and 2D NMR experiments.
