RESUMO
The absolute stereochemistry of the marine alkaloid (+)-(R)-tiruchanduramine was established via a convergent total synthesis in six steps and 15.5% overall yield from Fmoc-D-Dab(Boc)-OH.
Assuntos
Alcaloides/síntese química , Alcaloides/química , Técnicas de Química Sintética , Técnicas de Química Combinatória , Estrutura MolecularRESUMO
A simple method for the preparation of bromoferrocenes from stannylferrocenes is described: the preparation of 1,1'-dibromoferrocene is used as an example. Stannylferrocenes are reacted with bromine directly in dichloromethane to give bromoferrocenes in a self-indicating titration reaction. Also, an enhanced method of removal of the highly soluble organotin tin by-products formed in the preparation of 1,1'-diiodoferrocene from 1,1'-tri-n-butylstannylferrocene is reported allowing the preparation of large-scale quantities of 1,1'-diiodoferrocene, which is one of the most important starting materials in ferrocene chemistry.
RESUMO
The preparation of a range of amino acid derived guanidine organocatalysts is reported together with their application to the Michael addition of 2-hydroxy-1,4-napthoquinone to ß-nitrostyrene, achieving a maximum ee of 56%. Some insight into the mechanism was sought by using X-ray crystallography and a detailed study of the intra- and intermolecular hydrogen bonding is reported.
