RESUMO
Enantiopure phthalides 2 and 5-8 were synthesized via enantioresolution of the corresponding alcohols with a chiral auxiliary of camphorsultam dichlorophthalic acid, (1S,2R,4R)-(-)-CSDP acid 3, followed by solvolysis with KOH in MeOH and the catalytic oxidation of chiral glycols with iridium complex 28. The absolute configurations of phthalides 2 and 5-8 were determined by applying the (1)H-NMR anisotropy method of MalphaNP acid (4), 2-methoxy-2-(1-naphthyl)propionic acid, to the chiral synthetic precursory alcohols. In the case of 3-phenylphthalide (R)-(-)-7, the absolute configuration determined by the (1)H-NMR anisotropy method using MalphaNP acid 4 agreed with that by the X-ray crystallographic method. By applying these methods, 3-butylphthalide (S)-(-)-2, a fragrance component of essential oil of celery, has been synthesized in an enantiopure form, and its absolute configuration was unambiguously determined.
Assuntos
Apium/química , Benzofuranos/química , Benzofuranos/síntese química , Óleos Voláteis/química , Perfumes/química , Óleos de Plantas/química , Álcoois/síntese química , Álcoois/química , Cromatografia Líquida de Alta Pressão , Ésteres , Estrutura Molecular , Sílica Gel , Dióxido de Silício , Análise Espectral , EstereoisomerismoRESUMO
The stereochemistry of the asymmetric palladium-catalyzed reaction of allenes with iodobenzene followed by nucleophilic substitution reaction with sodium malonate and N-methylbenzylamine is described. On the basis of the absolute configuration of the product and the stereochemical result of a similar reaction of a chiral allene, the mechanism of the above asymmetric reactions is discussed.
Assuntos
Alcadienos/química , Compostos Organometálicos/química , Paládio/química , Catálise , Cromatografia Líquida de Alta Pressão , Cromatografia em Camada Fina , Indicadores e Reagentes , Iodobenzenos , Ligantes , Espectroscopia de Ressonância Magnética , Espectrometria de Massas , Conformação Molecular , Oxirredução , Espectrofotometria Infravermelho , Estereoisomerismo , TermodinâmicaRESUMO
The first Oppenauer oxidation of primary alcohols with acetone or 2-butanone by an amino alcohol-based Ir bifunctional catalyst was accomplished. The reaction proceeds with 1 mol % catalyst in acetone or 2-butanone at 30-80 degrees C to give the corresponding aldehydes in 33-96% yield.
RESUMO
[reaction: see text] A novel amino alcohol-based Ir bifunctional complex acts as an efficient catalyst for oxidative lactonization of 1,4- or 1,5-diols with a substrate-to-catalyst molar ratio of 200-1000 in acetone or butanone. The reaction proceeds with broad functional group tolerance to give lactone in high yield at room temperature. The catalyst precursor Cp*IrCl[OCH(2)C(C(6)H(5))(2)NH(2)] is isolated and characterized by a single-crystal X-ray analysis.
Assuntos
Lactonas/síntese química , Catálise , Cristalografia por Raios X , Indicadores e Reagentes , Irídio/química , Cetonas , Ligantes , Espectroscopia de Ressonância Magnética , Metais , Modelos Moleculares , OxirreduçãoRESUMO
New chiral sulfoxide-1,3-oxazoline ligands have been developed as chiral ligands for Lewis acid-catalyzed asymmetric Diels-Alder reactions. The use of chiral sulfinyl 1,3-oxazoline ligands in copper(II)-catalyzed asymmetric Diels-Alder reactions provided an endo cycloadduct as a major product with moderate enantioselectivity. A rationale is proposed for the mechanism of the asymmetric induction.