An iodine-catalyzed aerobicoxidative formal [4+2] annulation for the construction of polyfunctionalized pyridines in one step has been developed through the green reaction system of catalytic amounts of molecular iodine and amine in combination with oxygen. Various ketones and aldehydes were able to react with different chalcones and β, γ-unsaturated α-ketoesters through this reaction strategy. Synthetically
A highly efficient catalytic asymmetric [4+2] cycloaddition of silyloxyvinylindoles with [small beta],[gamma]-unsaturated [small alpha]-ketoesters has been accomplished by an avaliable chiral N,N[prime or minute]-dioxide/yttrium triflate complex. A widespread range of carbazole derivatives were obtained...
Highly enantioselective Michael addition of malonates to β,γ-unsaturated α-ketoesters catalyzed by chiral N,N′-dioxide-Yttrium(iii) complexes with convenient procedure
HighlyenantioselectiveMichaeladdition of malonates to beta,gamma-unsaturated alpha-ketoesters has been promoted by chiral N,N'-dioxide-Yttrium(iii) complexes, providing the corresponding products in excellent yields with 94-99% ee values.
A mild and facilesynthesis of polyfunctionalized pyridines from NH4OAc, β,γ-unsaturated α-ketoesters, and ketones/aldehydes has been reported through tandem three-component cyclization and aerobic oxidation using the combination of amine and metal catalysts. The synthetic value of the developed methodology was demonstrated by a gram-scale reaction and a wide range of substrates including naturally
Visible-Light Photocatalytic Aerobic Annulation for the Green Synthesis of Pyrazoles
作者:Ya Ding、Te Zhang、Qiu-Yun Chen、Chunyin Zhu
DOI:10.1021/acs.orglett.6b01867
日期:2016.9.2
A selective and high yielding synthesis of polysubstituted pyrazoles through a VLPC (visible light photoredox catalysis)-promoted reaction of hydrazine with Michael acceptors is reported. The method employs very mild reaction conditions and usesair as the terminal oxidant, which makes the process environmentally benign. Different types of Michael acceptors with various substituents can undergo the