Highly Efficient Asymmetric Trans-Selective Aziridination of Diazoacetamides and N-Boc-imines Catalyzed by Chiral Brønsted Acids
摘要:
A clean and fast (10 min) aziridination of diazoacetamides with N-Boc-imines, as well as N-Cbz-imines, catalyzed by chiral phosphoric acid (R)-5g in DCM at room temperature was developed, The excellent yields (89-97%), diastereoselectivities (trans/cis > 50:1), chemoselectivities (3:4 = >95:5), and enantioselectivities (88-98% ee) were achieved in the reaction.
We developed herein a new chiral Bronsted acid catalyst which is composed of two independent organic molecules, a chiral diol, and 2-boronobenzoic acid. In situ formation of a boronate ester was utilized as a key process to generate an active catalyst. This boronate ester assisted chiral carboxylic acid catalyst was successfully applied to the trans-aziridination of N-Boc and N-benzyl imines with N-phenyldiazoacetamide. This is the first catalyst to achieve high enantioselectivities using N-benzyl imines.
Trans-Selective Asymmetric Aziridination of Diazoacetamides and <i>N</i>-Boc Imines Catalyzed by Axially Chiral Dicarboxylic Acid
作者:Takuya Hashimoto、Nanase Uchiyama、Keiji Maruoka
DOI:10.1021/ja805635c
日期:2008.11.5
Axially chiral dicarboxylic acid (R)-1d catalyzed reaction of diazoacetamides and N-Boc imines provided a novel organocatalytic means for the formation of enantiomerically enriched N-Boc protected trans aziridines.
Highly Efficient Asymmetric <i>Trans-</i>Selective Aziridination of Diazoacetamides and <i>N</i>-Boc-imines Catalyzed by Chiral Brønsted Acids
A clean and fast (10 min) aziridination of diazoacetamides with N-Boc-imines, as well as N-Cbz-imines, catalyzed by chiral phosphoric acid (R)-5g in DCM at room temperature was developed, The excellent yields (89-97%), diastereoselectivities (trans/cis > 50:1), chemoselectivities (3:4 = >95:5), and enantioselectivities (88-98% ee) were achieved in the reaction.