ABSTRACT
A total synthesis of the racemic natural product tylophorine [(+/-)-1] has been demonstrated using the palladium-catalyzed carboamination method developed by Wolfe and co-workers. In this case, an electron-rich aryl bromide 18 was prepared in four steps and subjected to palladium-catalyzed Wolfe carboamination conditions with olefinic carbamate 7 to provide the racemic 2-(arylmethyl)pyrrolidine (+/-)-19 in good yield and was further elaborated to racemic tylophorine. This application of the Wolfe carboamination protocol as a key step to construct a natural product provides further evidence of the utility of the method.
Subject(s)
Alkaloids/chemical synthesis , Antineoplastic Agents, Phytogenic/chemical synthesis , Carbamates/chemistry , Indolizines/chemical synthesis , Palladium/chemistry , Phenanthrenes/chemical synthesis , Alkaloids/chemistry , Alkenes/chemistry , Amination , Antineoplastic Agents, Phytogenic/chemistry , Catalysis , Hydrocarbons, Brominated/chemistry , Hydrocarbons, Cyclic/chemistry , Indolizines/chemistry , Models, Chemical , Phenanthrenes/chemistry , Pyrrolidines/chemistry , StereoisomerismABSTRACT
The first discrete, self-complementary, quadruply hydrogen-bonded complexes based on the 2,6-diaminopurine (DAP) scaffold have been prepared; regioselective urea formation at the C2 amino group of the heterocycle allows intermolecular dimerization (K(dim) approximately 1-1.6 x 10(3) M(-1) in CDCl3) through a DADA hydrogen bonding motif.
