NHC/Nickel(II)‐Catalyzed [3+2] Cross‐Dimerization of Unactivated Olefins and Methylenecyclopropanes

Abstract

Cross‐dimerization of a methylenecyclopropane (1) and an unactivated alkene (2) with typical hydroalkenylation reactivity was observed for the first time by using a [NHC‐Ni(allyl)]BArF catalyst (NHC=N‐heterocyclic carbene). Results show that the C−C cleavage of 1 did not involve a Ni0 oxidative addition, which was crucial in former systems. Thus the method reported here emerges as a complementary method for attaining highly chemo‐ and regioselective synthesis of methylenecyclopentanes (3) with broad scope. An efficient NHC/NiII‐catalyzed rearrangement of 1 leads to the convergent synthesis of 3 in the presence of 2.

Assembly of iodinated indolo[1,2-c]quinazoline amines via I2/CHP-promoted cascade annulation of isocyanides and diarylalkynes

“…8 In the past few decades, transition metal-catalyzed cascade reactions based on isocyanide insertion have been extensively investigated, producing a great many high-value chemicals. 9 Cascade reactions have attracted great attention for their applications in the construction of complex molecules, and have undeniable advantages such as having only a single workup procedure and purification step without the isolation of the intermediates, and are looked upon as an atom- and step-economical, environmentally benign strategy for the construction of complex molecules. 10 Based on our continuing interest in isocyanide chemistry, 11 we assumed that the valuable indolo[1,2- c ]quinazoline framework bearing a vinyl iodide moiety could be constructed via an iodine-facilitated cascade annulation of a diarylalkyne and an isocyanide, which might proceed through an electrophilic addition, α-addition, dehydrohalogenation and intramolecular nucleophilic addition process.…”