RESUMO
[reaction--see text] Styryldiazoacetates are effective reactants for ylide formation that results in the formation of dihydropyrroles and dihydroazepines with high stereocontrol and in high yields.
Assuntos
Acetatos/química , Aldeídos/química , Azepinas/síntese química , Compostos de Diazônio/química , Iminas/química , Pirróis/síntese química , Estirenos/química , Catálise , Cristalografia por Raios X , Modelos Moleculares , EstereoisomerismoRESUMO
An effective methodology is reported for stereospecific epoxidation and aziridination via carbonyl ylide intermediates using rhodium(II) acetate catalyzed reactions of phenyl- and styryldiazoacetates with aldehydes, ketones, or imines.
Assuntos
Acetatos/química , Aziridinas/síntese química , Compostos Azo/química , Compostos de Epóxi/síntese química , Aziridinas/química , Compostos de Epóxi/química , Indicadores e Reagentes , Modelos Moleculares , Conformação Molecular , Estrutura Molecular , EstereoisomerismoRESUMO
The series of M2(hpp)4Cl2 complexes (hpp is the anion of 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine) from M = W to M = Pt has been completed by the preparation and characterization of those with M = W, Os, and Pt. W(hpp)4Cl2 (1) has a W-W distance of 2.250(2) A, is diamagnetic, and can be assigned a W-W triple bond based on a sigma 2 pi 4 electron configuration. Os2(hpp)4Cl2 (2) has an Os-Os distance of 2.379(2) A and displays a temperature-independent paramagnetism. It can be assigned a sigma 2 pi 4 delta 2 delta*2 configuration. Pt2(hpp)4Cl2 has a Pt-Pt distance of 2.440(1) A and is diamagnetic. A bond order of 1, based on a configuration in which only the sigma* orbital is empty, is consistent with these data.
