Nickel-Catalyzed Three-Component [3+2+2] Cocyclization of Ethyl Cyclopropylideneacetate and Alkynes—Selective Synthesis of Multisubstituted Cycloheptadienes

Concise and versatile multicomponent synthesis of multisubstituted polyfunctional dihydropyrroles

Tetra- and pentasubstituted polyfunctional dihydropyrroles have been concisely synthesized in high yields by two different processes of the one-pot multicomponent reactions (MCRs) of but-2-ynedioates 1, amines 2, and aldehydes 3 at room temperature or at 70 degrees C. The first one involves a domino hydroamination/nucleophilic addition/amidation-cyclization process and leads to the formation of tetrasubstituted polyfunctional dihydropyrroles 4. The second undergoes hydroamination/amidation/intramolecular cyclization/imine-enamine tautomerization sequence and results in pentasubstituted products 5. The structures of 4 and 5 were confirmed by single-crystal X-ray diffraction. These novel methodologies provide easy access to diversely multisubstituted polyfunctional dihydropyrrole libraries. The primary biological screening in vitro against HIV-1 has shown that 22 tested compounds have exhibited significant activity with IC(50) in micromolar range (38-58 microM).

Nickel-catalyzed carbocyanation of alkynes

Nickel-catalyzed carbocyanation reaction of alkynes is described. Alkynes undergo aryl- and allylcyanation reaction in the presence of nickel-phosphine catalysts to give a wide range of substituted acrylonitriles in highly stereo-, regio-, and chemoselective manners. Lewis acid cocatalysts, such as AlMe3, AlMe2Cl, and BPh3, are found to promote the arylcyanation significantly. The cooperative catalysis of nickel and Lewis acid also allows the carbocyanation reaction using alkenyl and alkyl cyanides.