Coumarin-3-formylpyrazoles have been synthesized and applied as 3-carbon synthons in reaction with 3-hydroxyoxindoles by using DABCO as the catalyst. A range of structurally diverse spiro-fused pentacyclic spirooxindoles, bearing a spirooxindole-γ-lactone and a 3,4-dihydrocoumarin substructure, could be smoothly obtained in good to excellent yields (up to 99%) with excellent diastereoselectivities
Organocatalytic Asymmetric Michael/Cyclization Cascade Reactions of 3-Hydroxyoxindoles/3-Aminooxindoles with α,β-Unsaturated Acyl Phosphonates for the Construction of Spirocyclic Oxindole-γ-lactones/lactams
Enantioselective Michael/cyclization cascade reactions of 3-hydroxyoxindoles/3-aminooxindoles with α,β-unsaturatedacyl phosphonates by using a cinchonine derived squaramide as the catalyst were developed. A broad range of spirocyclic oxindole-γ-lactones/lactams could be obtained in moderate to excellent yields (up to 98%) with good to excellent diastereo- and enantioselectivities (up to >99:1 dr and
Asymmetric hydrogenation of α-keto acid derivatives by rhodium-}amidophosphine-phosphinite{ catalysts
作者:Jean-François Carpentier、André Mortreux
DOI:10.1016/s0957-4166(97)00078-5
日期:1997.4
The enantioselective hydrogenation of several alpha-keto esters (3a-f, 5a-j), alpha-keto amides (7a-e) and isatine derivatives (9a-d) with a set of four representative neutral homogeneous rhodium-amidophosphine-phosphinite catalysts has been investigated. Trifluoroacetato-Rh-AMPP catalytic precursors promoted the rapid, efficient synthesis of aliphatic oc-hydroxy esters 4a-f in moderate to high enantioselectivities (66-95% ee), in contrast to most aromatic alpha-hydroxy esters 6a-j (8-81% ee). Best enantioselectivities for alpha-hydroxy amides 8a-e (85-95% ee) and dioxindoles 10a-d (80-94% ee) were obtained with chloro-Rh-AMPP precursors. It is proposed that, contrary to alpha-keto amides, alpha-keto esters do not chelate onto the rhodium center and that, in such circumstances, the asymmetric induction is mainly controlled by the steric hindrance around the C=O function. (C) 1997 Elsevier Science Ltd.
Organocatalytic, Enantioselective, Polarity-Matched Ring-Reorganization Domino Sequence Based on the 3-Oxindole Scaffold
A one-pot squaramide-catalyzed enantioselective ring-reorganization domino sequence (Michael addition/intramolecular ring-opening/lactamization) of 3-hydroxyoxindole and methyleneindolinone, which can be readily derived from 3-oxindole, has been established in this work. As a result, novel polycyclic quinolinone-spirooxindoles bearing three contiguous chiral centers were efficiently and step-economically assembled under mild conditions in high yields (up to 97%) with excellent enantioselectivities (up to >99% ee) and moderate to good diastereoselectivities (up to >95:5 dr).