Copper‐catalyzedconjugateaddition: A highlyenantioselectiveconjugateaddition of cyclicdiketones to β,γ‐unsaturated α‐ketoesters was achieved by using a two‐carbon‐linked N,N′‐dioxide‐Cu(OTf)2complex. Excellent yields (up to 99 %) and enantioselectivities (up to 99 % ee) were obtained with 2 mol % catalyst loading (see scheme). By using this method, adducts could be easily transformed into hexahydroquinolines
Catalytic asymmetric carbon–carbon bond forming reactions catalyzed by tetrahydroisoquinoline (TIQ) N,N′-dioxide ligands
作者:Zamani E.D. Cele、Sphelele C. Sosibo、Pher G. Andersson、Hendrik G. Kruger、Glenn E.M. Maguire、Thavendran Govender
DOI:10.1016/j.tetasy.2013.01.004
日期:2013.2
The use of TIQ-N,N′-dioxide ligands in asymmetric C–C bond forming reactions is described. In the Michael addition of cyclohexane-1,3-dione and malonates to β,γ-unsaturated α-ketoesters, excellent yields (up to 93%) and moderate to good enantioselectivities (70–89% ee) were obtained. The catalytic hetero-ene reaction of 2-methoxypropene with phenylglyoxal gave the ene product in excellent yield (95%)
The dinuclear zinc–ProPhenol complex is applied as efficient catalyst in the highly stereoselective tandem Michael addition/acetalization reactions of cyclic 1,3-diketones and β,γ-unsaturatedα-ketoesters. A variety of substrates are well-tolerated, and a broad range of synthetically and pharmaceutically useful chiral chromene derivatives are directly produced in good yields of up to 96% and good