926034-96-0Relevant academic research and scientific papers
Catalytic enantioselective Mannich-type reactions of ketoimines
Suto, Yutaka,Kanai, Motomu,Shibasaki, Masakatsu
, p. 500 - 501 (2007)
The first example of catalytic enantioselective Mannich-type reactions of simple ketoimines is described. The optimized conditions for aromatic ketoimines include the use of CuOAc-DTBM-SEGPHOS as the catalyst (10 mol %) and (EtO)2Si(OAc)2 as the trapping reagent (1 equiv) of the intermediate copper amide (generated via the addition of a copper enolate to the imine). The trapping reagent significantly facilitated the catalyst turnover. Excellent enantioselectivity was produced from a range of aromatic ketoimines, including heteroaromatic and ethyl-substituted ketoimines. The optimized conditions for aliphatic ketoimines include the use of CuOAc-4-tBu-cyclohexyl-DuPHOS as the catalyst and (EtO)3SiF as the trapping reagent. When aliphatic substrates were used, the enantioselectivity was in the 77-81% ee range. The products were converted to β,β-disubstituted amino acids, which are a very important class of chiral building blocks for natural product synthesis, pharmaceuticals, and conformationally regulated artificial proteins. Copyright
