Bifunctional Squaramide-Catalyzed Asymmetric [3 + 2] Cyclization of 2-(1-Methyl-2-oxoindolin-3-yl)malononitriles with Unsaturated Pyrazolones To Construct Spirooxindole-Fused Spiropyrazolones
作者:Ye Lin、Bo-Liang Zhao、Da-Ming Du
DOI:10.1021/acs.joc.9b01268
日期:2019.8.16
The present paper reports a highlystereoselectivesynthesis of spirooxindole-fused spiropyrazolones through the asymmetric [3 + 2] cyclization reaction of 2-(1-methyl-2-oxoindolin-3-yl)malononitriles with unsaturated pyrazolones under mild conditions. With only a 1 mol % bifunctional squaramide catalyst, a series of chiral dispirocyclic pyrazolone derivatives were attained in high yields (85–97%)
Enantioselective Construction of Bispirooxindoles via Squaramide‐Catalysed Cascade Michael/Cyclization Reaction
作者:Bo‐Liang Zhao、Ye Lin、Da‐Ming Du
DOI:10.1002/adsc.201900358
日期:2019.7.11
2‐(2‐oxoindolin‐3‐yl)malononitriles bearing multiple active sites were first used in asymmetric catalytic synthesis, which have been successfully applied to develop a bifunctional squaramide‐catalyzed cascade Michael/cyclizationreaction strategy. Various cyclopentene‐bispirooxindoles with three continuous stereocenters, two of which are quaternary spiro‐stereocenters, were constructed in good yields with excellent stereoselectivities
spirocyclopenteneoxindoles is an attractive target due to their potential biological activity. This work described the thiourea/silver dual catalytic (3 + 2)/Conia-ene type reaction of 2-(2-oxoindolin-3-yl)malononitrile with ortho-ethynyl substituted nitrostyrene. The reaction features mild conditions and good atom- and step-economy. Three new C–C bonds were formed within one synthetic step, providing
Synthetic and Theoretical Studies on the Reduction of Electron Withdrawing Group Conjugated Olefins Using the Hantzsch 1,4-Dihydropyridine Ester
作者:Simon J. Garden、Cristiano Ruch Werneck Guimarães、Marilza B. Corréa、César Augusto Fernandes de Oliveira、Angelo da Cunha Pinto、Ricardo Bicca de Alencastro
DOI:10.1021/jo034921e
日期:2003.11.1
The Hantzsch 1,4-dihydropyridine ester (1) has been observed to be a useful selective reducing agent for the reduction of electron-withdrawing conjugated double bonds. The rate of this reaction was observed to be dependent upon the nature of the conjugated substituents and, consequently, the electronic nature of the unsaturated double bond. Theoretical calculations confirmed the importance of the HOMO-LUMO gap for this reaction and implicated a hydride transfer, agreeing with the experimentally observed reaction rate order. The calculations also revealed the importance of a boatlike structure of the 1,4-dihydropyridine nucleus as well as a trans arrangement of the ester groups to facilitate the hydride transfer.
728. Hydroxytryptamines. Part IV. Synthesis and reactions of 2-3′-oxindolylethylamines