The reduction of the carbon-nitrogen double bond is an important transformation. Here we report our studies on a family of chiral organic catalysts able to promote the stereoselective reduction of ketimines with trichlorosilane. The very cheap, metal-free catalysts were easily prepared in one step from commercially available products, namely a chiral aminoalcohol and picolinic acid derivatives. The catalyst structure was extensively modified in a study that allowed to identify an extremely active species, able to promote the reduction on a large variety of substrates with high efficiency (up to 95% ee). A three component methodology has been also developed, where the enantiomerically enriched amine was isolated after performing the reaction by mixing a ketone and an amine in the presence of trichlorosilane and the catalyst. Its synthetic potentiality was demonstrated by employing the present metal-free catalytic procedure in the preparation of (S)-metolachlor, a potent and widely used herbicide.
Chiral Lewis base promoted trichlorosilane reduction of ketimines. An enantioselective organocatalytic synthesis of chiral amines / S. Guizzetti, M. Benaglia, R. Annunziata, F. Cozzi. - In: TETRAHEDRON. - ISSN 0040-4020. - 65:32(2009), pp. 6354-6363. [10.1016/j.tet.2009.06.015]
Chiral Lewis base promoted trichlorosilane reduction of ketimines. An enantioselective organocatalytic synthesis of chiral amines.
S. GuizzettiPrimo
;M. BenagliaSecondo
;R. AnnunziataPenultimo
;F. CozziUltimo
2009
Abstract
The reduction of the carbon-nitrogen double bond is an important transformation. Here we report our studies on a family of chiral organic catalysts able to promote the stereoselective reduction of ketimines with trichlorosilane. The very cheap, metal-free catalysts were easily prepared in one step from commercially available products, namely a chiral aminoalcohol and picolinic acid derivatives. The catalyst structure was extensively modified in a study that allowed to identify an extremely active species, able to promote the reduction on a large variety of substrates with high efficiency (up to 95% ee). A three component methodology has been also developed, where the enantiomerically enriched amine was isolated after performing the reaction by mixing a ketone and an amine in the presence of trichlorosilane and the catalyst. Its synthetic potentiality was demonstrated by employing the present metal-free catalytic procedure in the preparation of (S)-metolachlor, a potent and widely used herbicide.Pubblicazioni consigliate
I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.