Enantiospecific Synthesis of (+)- and (−)-Ferruginine from l-Glutamic Acid. Synthesis of Tropanes via Intramolecular Iminium Ion Cyclization
摘要:
Iminium ions, generated by decarbonylation of N-benzyl-5-[1-(methoxycarbonyl)-4-oxopentyl]-prolines, prolines, undergo intramolecular cyclization to afford 2,4-disubstituted tropanes in good yields. This transformation is also shown to be a stereospecific reaction. The value of these substituted tropanes has been demonstrated by functional group manipulation, leading to the enantiospecific synthesis of (+)-ferruginine, an alkaloid isolated from Darlinga ferruginea, and its unnatural enantiomer, (-)-ferruginine.
Intramolecular Diels−Alder/1,3-Dipolar Cycloaddition Cascade of 1,3,4-Oxadiazoles
摘要:
Full details of a systematic exploration of the intramolecular [4+2]/[3+2] cycloaddition cascade of 1,3,4-oxadiazoles are disclosed in which the scope and utility of the reaction are defined.