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A palladium-catalyzed 1:2 linear/cyclic cross-trimerization of alkyne with alkenes in presence of molecular oxygen as the sole oxidant is reported. The controlled reaction mechanism yields a series of 1,3,5-trienes and 1,2,4,5-tetrasubstituted benzenes with high chemoselectivity.

Selective C-H bond alkynylation toward modular access to material and pharmaceutical molecules is of great desire in modern organic synthesis. Reported herein is Ir(III)-catalyzed regioselective C-H alkynylation of ketones and esters, which is generally applicable for the rapid construction of molecular complexity. This protocol provides a complementary process for conventional alkyne synthesis. Further functionalization of carbonyl-derived material molecules and pharmaceuticals demonstrates the potential synthetic utility of this methodology. [ABSTRACT FROM AUTHOR]

The first attempt at utilizing N-tosylhydrazones as two-carbon synthons has been successfully achieved, which underwent a copper-mediated [3 + 2] oxidative cyclization reaction to afford 2,3,5-trisubstituted furans in moderate to good yields. The features of this method include inexpensive metal catalyst, readily available substrates, high regioselectivity, and convenient operation. The studies provide important approaches for further exploration of the powerful and diverse reaction abilities of N-tosylhydrazones. [ABSTRACT FROM AUTHOR]

A novel palladium-catalyzed oxidative annulation reaction for the C-O, C-N bond formations is developed. The intramolecular cyclocarbonylation provides an efficient and direct approach for the construction of valuable 1,3,4-oxadiazole-2(3H)-ones and their derivatives. The reaction also facilitated the convenient synthesis of BMS-191011, an opener of the cloned large-conductance Ca2+-activated potassium channel, providing an attractive method for medicinal chemistry. [ABSTRACT FROM AUTHOR]

A direct and facile palladium-catalyzed C-H bond oxidative carbonylation reaction and oxidative cyclization for the synthesis of polycyclic aromatic hydrocarbons (PAHs) is reported herein. The intramolecular cyclocarbonylation, through C-H activation and C-C, C-O bond formations under mild conditions, proceeds smoothly with good functional group tolerance in high to excellent yields. The intramolecular palladium-catalyzed direct oxidative C-H bond functionalization for the C-O bond formation is also demonstrated, which provides an efficient approach for the construction of various PAHs. [ABSTRACT FROM AUTHOR]

A simple, practical, and highly efficient synthesis of pyrazoles and indazoles via copper-catalyzed direct aerobic oxidative C(sp²)-H amination has been reported herein. This process tolerated a variety of functional groups under mild conditions. Further diversification of pyrazoles was also investigated, which provided its potential for drug discovery. [ABSTRACT FROM AUTHOR]