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An array of spiro[benzofuran-2,3′-pyrazol]-3-imines with diverse functional groups were readily assembled from aurone-derived azadienes and in - situ generated nitrilimines under mild conditions. The transformation was performed in a regio- and diastereoselective fashion, in which a synergetic [2+3] cycloaddition pathway was likely involved. This novel methodology has extended the synthetic application of aurone-derived azadienes as a kind of two-atom synthon. [ABSTRACT FROM AUTHOR]

An efficient, one-pot, three-component [3+2] cycloaddition reaction of azomethine ylide obtained from α-dicarbonyl compounds (cyclic and acyclic diketone or keto ester) and amino acids with maleimides under catalyst-free conditions has been developed. This cascade protocol shows high efficiency and remarkable functional group tolerance, and the ubiquitous succinimide-fused pyrrolizidines with a highly compact and strained scaffold were obtained with high yield and excellent diastereoselectivity. Furthermore, this novel and atom-economical strategy could be performed on a gram scale with comparable reaction efficiency. [ABSTRACT FROM AUTHOR]

We have developed a unique approach for the thermally promoted cycloaddition of cyclohexadienone-tethered allenes to form a versatile cyclobutane-fused oxygen-containing tricyclic framework in an environmentally friendly and atomic economic fashion with high regioselectivity. The reaction encompasses a broad substrate scope and functional group tolerance of cyclohexadienone moieties. Moreover, the cycloaddition was also applicable to the late-stage functionalization of pharmaceutically relevant compounds. [ABSTRACT FROM AUTHOR]

We have developed a one-pot synthesis of benzo[b]fluorenones via a cobalt-catalyzed [3+2] annulation of oxabicyclic alkenes followed by a ring-opening/dehydration sequence in good to excellent yields. With the use of 2-(1-methylhydrazinyl)pyridine (MHP), first explored by our group as the bidentate directing group in C–H functionalization of benzoic hydrazides, the new reaction sequence proceeded smoothly and tolerated a wide range of functional groups, featuring facile scalability. Notably, oxygen served as the green oxidant in the reaction system. Careful tuning of the reaction parameters assured the direct synthesis of benzo[b]fluorenones through aromatization of the dihydroepoxybenzofluorenone intermediate. [ABSTRACT FROM AUTHOR]

A cobalt‐catalyzed direct C−H/N−H functionalization of benzoyl hydrazide with isocyanide by utilizing 2‐(1‐methylhydrazinyl)pyridine (MHP) as a bidentate directing group has been developed. This formal [4+1] cycloaddition protocol showed high efficiency and remarkable functional group tolerance, and the ubiquitous 3‐iminoisoindolinones were obtained in good to excellent yields in the presence of the earth‐abundant cobalt catalyst. Moreover, this transformation was accomplished by employing environmentally friendly oxygen as the sole oxidant in the absence of any other additives. [ABSTRACT FROM AUTHOR]

Abstract: A cobalt‐catalyzed C−H carbonylation of benzoyl hydrazides has been developed by using 2‐(1‐methylhydrazinyl)pyridine as the bidentate directing group. This transformation is mild, efficient, operationally simple, and highly functional‐group‐tolerant. The protocol has generated a broad range of phthalimide derivatives in good to excellent yields. The ligand moiety can be readily removed through hydrogenolysis. [ABSTRACT FROM AUTHOR]