Organocatalyzed enantioselective aldol reaction of 1H-pyrrole-2,3-diones

Regiodivergent condensation of 5-alkoxycarbonyl-1H-pyrrol-2,3-diones with cyclic ketazinones en route to spirocyclic scaffolds

The condensation of 5-alkoxycarbonyl-1H-pyrrolediones with cyclic ketazinones was systematically investigated. It was discovered that the regioselectivity of this reaction can be easily swapped between two alternative directions affording derivatives of partially hydrogenated indole or benzofurane. The control of this regioselectivity is efficiently governed by steric effects at the hydrazone moiety of the ketazinone reagent.

Organocatalytic asymmetric Henry reaction of 1H-pyrrole-2,3-diones with bifunctional amine-thiourea catalysts bearing multiple hydrogen-bond donors

For the first time, a catalytic asymmetric Henry reaction of 1H-pyrrole-2,3-diones was achieved with a chiral bifunctional amine-thiourea as a catalyst possessing multiple hydrogen-bond donors. With this developed method, a range of 3-hydroxy-3-nitromethyl-1H-pyrrol-2(3H)-ones bearing quaternary stereocenters were obtained in acceptable yield (up to 75%) and enantioselectivity (up to 73% ee).

New method for in situ generation of enolate-iminium 1,4-dipoles for [4 + 2] and [4 + 1] dipolar heterocycloaddition reactions

Thermolysis ofN-(diphenylenamino)pyrrolediones proceeds with formation of dihydropyrazolone 1,4-dipoles. [4 + 4] Homodimerizations and a series of [4 + 2] and [4 + 1] cycloadditions of these species with various dipolarophiles were investigated.