Highly enantioselective synthesis of naphthoquinones and pyranonaphthoquinones catalyzed by bifunctional chiral bis-squaramides
作者:Nagaraju Molleti、Vinod K. Singh
DOI:10.1039/c5ob00105f
日期:——
bis-squaramide catalyzed conjugate addition of 2-hydroxy-1,4-naphthoquinone to 2-enoylpyridines. Some of the Michael products have been successfully converted into various enantioenriched pyranonaphthoquinone derivatives. The protocol is further extended to the synthesis of various 4-hydroxycoumarinderivatives under mild conditions.
Diastereo- and enantioselective direct vinylogous Michael addition of γ-substituted butenolides to 2-enoylpyridines catalyzed by chiral bifunctional amine-squaramides
The diastereo- and enantioselectivedirectvinylogousMichaeladdition reaction of [gamma]-substituted butenolides to 2-enoylpyridines has been achieved. A range of [gamma],[gamma]-disubstituted butenolide derivatives, bearing two consecutive tri- and tetrasubstituted stereogenic...
Enantioselective synthesis of chiral α,β-unsaturated γ-substituted butyrolactams by organocatalyzed direct asymmetric vinylogous Michael addition of α,β-unsaturated γ-butyrolactam to 2-enoylpyridines
organocatalyzed direct asymmetric vinylogous Michaeladdition reaction of α,β-unsaturated γ-butyrolactam to 2-enoylpyridines has been developed with a chiral bifunctional amine-squaramide as the catalyst. This approach provides easy access to a series of optically active α,β-unsaturated γ-substituted butyrolactams in high yields (up to 99%) with excellent diastereoselectivities (up to >99 : 1) and enantioselectivities
Unexpected manganese(iii) acetate-mediated reactions of β-enamino carbonyl compounds with 1-(pyridin-2-yl)-enones under mechanical milling conditions
作者:Zi Liu、Guang-Peng Fan、Guan-Wu Wang
DOI:10.1039/c2cc36360g
日期:——
The solvent-free reactions of beta-enamino carbonylcompounds with 1-(pyridin-2-yl)-enones in the presence of manganese(iii) acetate dihydrate unexpectedly afforded 2-acyl-3-aryl-6,7-dihydro-4(5H)-benzofuran derivatives under mechanical milling conditions.
Asymmetric Diels-Alder reactions between aza-chalcone and cyclopentadiene (CP) catalyzed by the binaphthol-titanium (BINOL – Ti) in the presence of HMPA (80 mole %) were studied. The products were obtained with up to 87% ees.