Enantioselective sequential vinylogous Michael addition–cyclization reactions of vinyl malononitriles with isatylidene malononitrile were accomplished usingl-proline derived bifunctional thiourea.
First asymmetric decarboxylative cyanomethylation of isatins is reported herewith using bifunctional thiourea derived from l-proline in good yields and enantioselectivities. This strategy enables the construction of various 3-cyanomethylene substituted 3-hydroxyoxindoles in enantioselective manner. Enantioselective synthesis of CPC-1 alkaloid has been accomplished in fewer steps.
Diverseb ispiro-3,4-dihydropyrans consisting of oxindole moietiesw itht hree contiguous chiralc enters and vicinal quaternary stereocenters were synthesized with very good yields of up to 92 %a nd excellent enantioselectivity of up to 99 % ee by using ap roline-derived thiourea organocatalyst.
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