RESUMO
Primary-secondary diamine catalysts were used to catalyze the asymmetric Robinson annulation to synthesize multiply substituted fluorinated chiral cyclohexenones with two contiguous stereogenic centers, one of which is a fluorinated quaternary chiral center, with excellent enantioselectivities and diastereoselectivities in moderate to good yields.
Assuntos
Cicloexanonas/síntese química , Diaminas/química , Hidrocarbonetos Fluorados/síntese química , Catálise , Cicloexanonas/química , Hidrocarbonetos Fluorados/química , Espectroscopia de Ressonância Magnética , Modelos Moleculares , EstereoisomerismoRESUMO
The first enantioselective Michael addition of alpha-cyanoketones to alpha,beta-unsaturated trifluoromethyl ketones using a novel piperazine-thiourea catalyst was described. The resulting alpha-trifluoromethyldihydropyrans were obtained in high yields and with up to 95% ee within a short reaction time. A useful transformation of the chiral adduct was also illustrated.
RESUMO
Single-crystal-to-single-crystal transformation of one-dimensional 4d-4f coordination polymers has been investigated for the first time. More importantly, we observed the transformation of a meso-helical chain to a rac-helical chain as a function of the temperature.
RESUMO
[reaction: see text] A series of chiral pyrrolidinylmethanol-based dendritic ligands were synthesized for application in enantioselective aryl transfer reactions to aldehydes with the (ArBO)3/ZnEt2 system in up to 98% ee.
RESUMO
[structure: see text] A new series of oligoanthranilamides has been synthesized starting from suitably modified p-phenylenediamine and p-phthalic acid derivatives. Due to strong intramolecular three-center hydrogen bonds, the new oligomers self-assemble into highly stable straight and planar molecular ribbons, which have been characterized by X-ray crystallography and 1H NMR, IR, and UV-vis spectroscopy.
