Lithiated 3-tosylpropanal and 4-tosyl-2-butanone dimethyl acetals as β-acylvinyl anion equivalents for the synthesis of unsaturated 1,4-dicarbonyl compounds and α,β-butenolides
作者:Pedro Bonete、Carmen Nájera
DOI:10.1016/0040-4020(95)00026-5
日期:1995.2
chlorides affords, after p-toluenesulfinic acid elimination, ene-1,4-dicarbonyl compounds in a stereoselective manner. In the case of compound 7a, derived from acrolein, sequential monolithiation and reaction with carbonyl compounds give cyclicacetals, which after oxidation and elimination of p-toluenesulfinic acid are transformed into α,β-butenolides.
A new asymmetric organocatalytic synthesis of spirocyclopropaneoxindoles has been developed. The method is based on the Michael addition of N-Boc-protected 3-chlorooxindole to unsaturated 1,4-dicarbonyl compounds, affording trans-substituted spirocyclopropaneoxindolederivatives in high diastereo- and enantioselectivity.
Catalyst-Controlled, Enantioselective, and Diastereodivergent Conjugate Addition of Aldehydes to Electron-Deficient Olefins
作者:S. B. Jennifer Kan、Hiroki Maruyama、Matsujiro Akakura、Taichi Kano、Keiji Maruoka
DOI:10.1002/anie.201705546
日期:2017.8.1
A chiral-amine-catalyzed enantioselective and diastereodivergent method for aldehyde addition to electron-deficient olefins is presented. Hydrogen bonding was used as a control element to achieve unusual anti selectivity, which was further elucidated through mechanistic and computational studies.
Fiaud’s acid (trans-1-hydroxy-2,5-diphenylphospholane 1-oxide), a phospholane-based phosphinic acid, is introduced as an efficient chiral Brønsted acidcatalyst that mediates the asymmetric Friedel–Crafts alkylation of indoles with 2-butene-1,4-diones. With a catalyst loading of 10 mol %, the reaction proceeded smoothly to afford 2-(indol-3-yl)butane-1,4-diones in high yield (up to 82%) and high enantioselectivity
Conjugateaddition to 1,4-dicarbonylbut-2-enes will generate an α-stereogenic center with respect to one of the carbonyl groups, which informally, can be considered as an inversion of normal reactivity patterns or umpolung protocol. In this paper, the addition of tert-butyl mercaptan to 1,4-dicarbonylbut-2-enes including (E)-4-oxo-4-arylbutenamides and (E)-4-oxo-4-arylbutenones has been developed,