Pd-Catalyzed Direct C-H Activation for the C5-Olefination of Methyleneindolinones.

The direct C-H activation without directing groups can realize the para-selectivity, which is a powerful and concise approach for functionalization of arenes. Utilizing the strategy, a C5-olefination of methyleneindolinones has been successfully developed by palladium-catalyzed direct C-H activation, which provides an expeditious access to 5-vinylindolin-2-ones with high regioselectivity. The protocol is distinguished by a mild reaction system avoiding ligand and high temperature. The kinetic isotope experiments indicate that the C-H bond cleavage is the rate-limiting step.

Construction of multiple bonds via a domino reaction of trifluoroacetimidoyl nitriles with in situ generated bis-nucleophiles.

A transition-metal-free double addition/double rearrangement domino reaction affording CF3-substituted pyrimidines was developed, which enables the one-pot construction of five new bonds, namely three C-C bonds and two C-N bonds. The keys to achieve this highly efficient reaction include the delicate design of the bis-nucleophiles in situ generated from the dimerization of alkyl nitriles and the use of trifluoroacetimidoyl nitriles containing C[double bond, length as m-dash]N, C[triple bond, length as m-dash]N, and CF3 groups as the reactant. The mechanistic studies by the experiments and DFT calculations reveal that the transformation involves two addition and two unprecedented rearrangement processes.