one-pot, two-step process was disclosed for production of chiral α,β-epoxy ketonesfrom benzaldehydes and acetophenones catalyzed by imidazolium-modified poly(l-leucine). Two effective reaction systems with complementary high enantioselectivities (up to 98% ee) or satisfactory yields (up to 89%) have been developed. Importantly, the poly(aminoacid) catalyst can be easily recovered and recycled for ten
Diaryl-2-pyrrolidinemethanols catalyzed enantioselective epoxidation of α,β-enones: new insight into the effect of structural modification of the catalyst on reaction efficiency
作者:Alessandra Lattanzi、Alessio Russo
DOI:10.1016/j.tet.2006.10.005
日期:2006.12
Catalytic enantioselectiveepoxidation of α,β-unsaturated ketones promoted by diaryl-2-pyrrolidinemethanols and tert-butyl hydroperoxide (TBHP) is described. Investigation on structural modifications of the diaryl-2-pyrrolidinemethanols showed that fine tuning of the stereoelectronics of the substituents on the aryl moiety is important to achieve high efficiency. By employing a structurally optimized
Asymmetric synthesis of new γ-butenolides via organocatalyzed epoxidation of chalcones
作者:Lucas C. C. Vieira、Bianca T. Matsuo、Lorena S. R. Martelli、Mayara Gall、Marcio W. Paixão、Arlene G. Corrêa
DOI:10.1039/c7ob00165g
日期:——
medicinally important agents. In this work we describe a new metal-free sequential strategy for the asymmetric synthesis of substituted γ-butenolides having epoxychalcones as the advanced intermediate. Using the optimized reaction conditions, we were able to carry out the three-step sequence, epoxidation, olefination and hydrolysis, with only one single chromatographic purification of the final product
Enantioselective (up to 87% ee) epoxidation of a variety of α,β-enones to form α,β-epoxy ketones is described using a series of fluorous α,α-diaryl-l-prolinols as bifuncational organocatalysts and tert-butyl hydrogenperoxide (TBHP) as an oxidant.
A highly efficient catalytic kinetic resolution of 2,3-epoxy 3-aryl ketones via asymmetric ring-opening with pyrazole derivatives has been achieved by using a chiral N,N′-dioxide–Sc(iii) complex as the catalyst.