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A novel and regioselective umpolung synthesis of spirooxindoles has been developed by cooperative NHC-Lewis acid-mediated formal [3 + 2] annulations of alkynyl aldehydes with isatins. In most cases, the reactions proceeded via a(3)-d(3) umpolung of alkynyl aldehydes resulting in spirooxindole butenolides. In a few cases, spirooxindole furan-3(2H)-ones were formed as the major products via an a(1)-d(1) umpolung process by controlling the reaction temperature. These newly formed spirooxindoles could provide promising candidates for chemical biology and drug lead discovery.

Perhydroindolic acids, the by-products obtained in the industrial production of a trandolapril intermediate, were used as chiral organocatalysts in asymmetric Michael addition reactions of aldehydes to nitroolefins. These proline-like catalysts are unique for their rigid bicyclic structure with two H atoms attached to the bridgehead C atoms lying on the opposite side of the ring. They therefore showed high efficiency in asymmetric Michael additions of aldehydes to nitroolefins. Under the optimal conditions, excellent diastereo- and enantioselectivities (up to 99/1 dr and 98% ee) were obtained with high chemical yields for a series of aldehydes and nitroolefins using only 5 mol% catalyst loading. The methodology features easily available catalysts, high catalytic efficiency and environmentally green procedures., (This journal is © The Royal Society of Chemistry 2012)

Cationic Lewis acid complexes [Sc(pyridyl-bis(oxazolinyl)](Cl(2))SbF(6) 1a and 1b catalyze aldol reactions with ethyl glyoxylate with enantioselectivities ranging from 90 to 99% ee and syn reaction diastereoselections ranging from 90:10 to 95:5. [reaction: see text]