Asymmetric aldol reactions of isatins catalyzed by phthalimido-prolinamide

Cu(ii)-thiophene-2,5-bis(amino-alcohol) mediated asymmetric Aldol reaction and Domino Knoevenagel Michael cyclization: a new highly efficient Lewis acid catalyst

The highly efficient Lewis acid-catalytic system Cu(ii)-thiophene-2,5-bis(amino-alcohol) has been developed for enantioselective Aldol reaction of isatin derivatives with ketones. The new catalytic system also proved to be highly enantioselective for the one pot three-component Domino Knoevenagel Michael cyclization reaction of substituted isatin with malononitrile and ethylacetoacetate. The chiral ligand (2S,2'S)-2,2'-((thiophene-2,5-diylbis(methylene))bis(azanediyl))bis(3-phenylpropan-1-ol) (L1) in combination with Cu(OAc)2·H2O employed as a new Lewis acid catalyst, furnished 3-substituted-3-hydroxyindolin-2-ones derivatives (3a-s) in good to excellent yields (81-99%) with high enantioselectivities (up to 96% ee) and spiro[4H-pyran-3,3-oxindole] derivatives (6a-l) in excellent yields (89-99%) with high ee (up to 95%). These aldol products and spiro-oxindoles constitute a core structural motif in a large number of pharmaceutically active molecules and natural products.

Eco‐friendly Polyethylene Glycol‐400 as a Rapid and Efficient Recyclable Reaction Medium for the Synthesis of Anticancer Isatin‐linked Chalcones and Their 3‐Hydroxy Precursor

Isatin chalcones and their 3‐hydroxy precursors are shown to possess potential anticancer activity and are also versatile substrates and key intermediates for the synthesis of a large variety of bioactive spiro‐oxindoles. An environmental friendly tandem synthesis, using PEG 400 as green solvent cum phase transfer catalyst, for a series of 3‐hydroxy‐2‐oxindoles and 3‐methylene‐2‐oxindoles has been developed. Reported one‐pot sustainable synthetic strategy was compared with the conventional method and was found to be superior to existing two‐step syntheses in terms of simplicity, product yield, and reaction time and have a large substrate scope.

Catalytic enantioselective aldol reactions

Recent developments in catalytic asymmetric aldol reactions have been summarized.