Dinesh Kumar Rayabarapu

Nickel-catalyzed highly chemoselective cocyclotrimerization of arynes with allenes: a novel method for 10-methylene-9,10-dihydrophenanthrenesElectronic supplementary information (ESI) available: synthesis and characterization data of compounds 3. See http://www.rsc.org/suppdata/cc/b3/b315795d/

The NiBr(2)(dppe)-Zn system effectively catalyzes the [2+2+2] cocyclotrimerization of arynes with allenes, leading to 10-methylene-9,10-dihydrophenanthrenes in moderate to good yields. The cocyclotrimerization is highly selective with only the internal double bond of the allenes being involved in the reaction.

Three-Component Synthesis of 1,4-Diazepin-5-ones and the Construction of γ-Turn-like Peptidomimetic Libraries

The parallel synthesis of gamma-turn-inspired peptidomimetic libraries has been demonstrated through two approaches toward the preparation of 1,4-diazepin-5-ones. In the first approach, 1,4-diazepin-5-ones scaffolds were prepared on gram scale and subsequently diversified to produce libraries. In a second approach, libraries of 1,4-diazepin-5-ones were produced directly through a three-component strategy that maximizes the diversity obtained in a single step.

Novel cyclization and reductive coupling of bicyclic olefins with alkyl propiolates catalyzed by nickel complexes

In this article, new metal-mediated cyclization and reductive coupling reactions of bicyclic olefins with alkynes are described. Oxabicyclic alkenes undergo cyclization with alkyl propiolates at 80 C catalyzed by nickel complexes to give benzocoumarin derivatives in high yields. The reaction of bicyclic alkenes (oxa- and azacyclic alkenes) with alkyl propiolates at room temperature in the presence of the same nickel complex gave 1,2-dihydro-napthelene derivatives in good-to-excellent yields. This reductive coupling reaction proceeds under very mild conditions in complete regio- and stereoselective fashion. A mechanism to account for the coumarin formation and the reductive coupling is proposed.

Synthesis of epoxybenzo[d]isothiazole 1,1-dioxides via a reductive-Heck, metathesis-sequestration protocol

An atom-economical purification protocol, using solution phase processing via ring-opening metathesis polymerization (ROMP) has been developed for the synthesis of tricyclic sultams. This chromatography-free method allows for convenient isolation of reductive-Heck products and reclamation of excess starting material via sequestration involving metathesis catalysts and a catalyst-armed Si-surface.

Nickel-catalyzed regioselective carbocyclization of ortho-halophenyl ketones with propiolates: an efficient route to disubstituted indenols

Carbocylization of o-halophenyl ketones with propiolates in the presence of Ni(dppe)Br2 and Zn powder in acetonitrile at 80 degrees C afforded the corresponding 2,3-disubstituted indenols.