RESUMEN
This paper describes the stereoselective total syntheses of (+)-1-deoxygalactonojirimycin and (-)-1-deoxygulonojirimycin via new chiral building blocks syn,anti,syn-oxazine 11a and syn,syn,anti-oxazine 13a. These were accomplished in four steps in 44.1 and 33.7% overall yields, respectively. These chirons were derived from the stereoselective addition of a nucleophile to the corresponding aldehydes of syn,anti-oxazine 10 and syn,syn-oxazine 12. Furthermore, this paper describes the stereochemical analysis of three types of chiral 1,3-oxazines; anti,syn-, syn,anti-, and syn,syn-oxazines using the NOESY technique.
RESUMEN
Concise and stereocontrolled syntheses of (+)-hyacinthacine A2 and sphingofungin B were achieved via a diastereomerically enriched oxazine intermediate. The key strategies include palladium(0)-catalyzed intramolecular oxazine formation and diastereoselective nucleophilic addition to an aldehyde. (+)-Hyacinthacine A2 was synthesized in 13 steps and 10.2% overall yield and the synthesis of sphingofungin B proceeded in a linear sequence over 15 steps and 6.9% overall yield from (R)-methyl 2-benzamido-3-((tert-butyldimethylsilyl)oxy)propanoate.
Asunto(s)
Productos Biológicos/síntesis química , Oxazinas/química , Alcaloides de Pirrolicidina/síntesis química , Aminoácidos/síntesis química , Aminoácidos/química , Aspergillus fumigatus/química , Productos Biológicos/química , Ácidos Grasos Insaturados/síntesis química , Ácidos Grasos Insaturados/química , Liliaceae/química , Oxazinas/síntesis química , Paladio/química , Alcaloides de Pirrolicidina/química , EstereoisomerismoRESUMEN
The possibility has been raised that Folium mori is clinically effective for the treatment and prevention of diabetes. In the present study, the effects of Folium mori on cell proliferation and expression of neuropeptide Y (NPY) in the dentate gyrus of rats with streptozotocin (STZ)-induced diabetes were investigated by 5-bromo-2'-deoxyuridine (BrdU) immunohistochemistry and NPY immunohistochemistry. In rats with STZ-induced diabetes, cell proliferation and NPY expression in the dentate gyrus were suppressed, and treatment with Folium mori was shown to increase new cell formation and NPY expression in the dentate gyrus in both normal rats and those with STZ-induced diabetes. In light of previous studies, this result appears to indicate that increased expression of NPY in the dentate gyrus induced by treatment with Folium mori is associated with the observed effect of Folium mori extract on cell proliferation. Based on the present results, it is suggested that Folium mori treatment may aid in the recovery from the central nervous system complications of diabetes mellitus.