Kinetic Studies on the Palladium(II)-Catalyzed Oxidative Cross-Coupling of Thiophenes with Arylboron Compounds and Their Mechanistic Implications.

Reaction orders for the key components in the palladium(II)-catalyzed oxidative cross-coupling between phenylboronic acid and ethyl thiophen-3-yl acetate were obtained by the method of initial rates. It turned out that the reaction rate not only depended on the concentration of palladium trifluoroacetate (reaction order: 0.97) and phenylboronic acid (reaction order: 1.

Regioselective oxidative Pd-catalysed coupling of alkylboronic acids with pyridin-2-yl-substituted heterocycles.

A total of 19 alkylated heterocycles (thiophenes, benzothiophenes, pyrroles, furans) were prepared (36-99% yield) from the respective pyridin-2-yl-substituted precursors employing alkylboronic acids as the C-H alkylating reagents in an oxidative (Ag2CO3 and 2,6-dimethyl-1,4-benzoquinone as oxidants) Pd-catalysed coupling reaction.

Modular synthesis of phenanthro[9,10-c]thiophenes by a sequence of C-H activation, suzuki cross-coupling and photocyclization reactions.

A total number of 15 different 3,4-diarylthiophenes were synthesized, which bear a chlorine atom in ortho-position of one of the aryl substituents. One aryl group was introduced by an oxidative cross-coupling reaction, involving a CH activation at C4(3) of the thiophene core. The other aryl group was in most cases introduced by a Suzuki cross-coupling reaction, which succeeded the oxidative cross-coupling step.

Regioselective oxidative coupling reactions of 3-substituted thiophenes with arylboronic acids.

Under optimized conditions, 3-substituted thiophenes (EWG = COOEt, PO(OEt)(2)) undergo a facile and regioselective oxidative coupling reaction at carbon atom C4. The reactions were performed with various aryl boronic acids as nucleophiles in the presence of silver oxide (2.0 equiv), cesium trifluoroacetate (tfa) (1.