Synthesis of 1,2-Benzothiazines by a Rhodium-Catalyzed Domino C-H Activation/Cyclization/Elimination Process from S-Aryl Sulfoximines and Pyridotriazoles.

A method for the synthesis of a large number of 1,2-benzothiazines bearing pyridyl as well as carbonyl groups is developed from rhodium-catalyzed carbene insertions into aromatic C-H bonds of S-aryl sulfoximines using pyridotriazoles by denitrogenative cyclization followed by the elimination of alcohols. The present method involves the N-H/C-H activation of simple alkyl aryl sulfoximines and has the advantages of a broad substrate scope, high functional group tolerance, and good regioselectivity.

Synthesis of Azulen-1-yl Ketones via Oxidative Cleavage of C-C Multiple Bonds in N-Sulfonyl Enamides and 1-Alkynes under Air and Natural Sunlight.

A synthetic method to prepare azulen-1-yl ketones was developed via oxidative cleavage of the C-C double bond in the reaction of easily obtainable N-sulfonyl enamides with Cs2CO3 under air and natural sunlight and in the absence of a photosensitizer. Oxidative cleavage of C-C triple bonds was also demonstrated for the synthesis of azulen-1-yl ketones via a tandem Cu-catalyzed [3 + 2] cycloaddition, Rh-catalyzed arylation, photooxygenation, and ring-opening reaction in one pot under air and natural sunlight.

Synthesis of Cinnolin-3(2H)-one Derivatives from Rh-Catalyzed Reaction of Azobenzenes with Diazotized Meldrum's Acid.

A synthetic method of a wide range of cinnolin-3(2H)-one derivatives is developed from the reaction of symmetrical as well as unsymmetrical azobenzenes with diazotized Meldrum's acid via Rh-catalyzed C-H alkylation followed by cyclization.

Synthesis of fluorenes via tandem copper-catalyzed [3 + 2] cycloaddition and rhodium-catalyzed denitrogenative cyclization in a 5-exo mode from 2-ethynylbiaryls and N-sulfonyl azides in one pot.

An efficient synthetic method of fluorenes having an enamine moiety at C-9 methylene bridge is developed from N-sulfonyl-4-biaryl-1,2,3-triazole derivatives via Rh-catalyzed denitrogenative cyclization in a 5-exo mode. Rh-catalyzed denitrogenative cyclization followed by catalytic hydrogenation produces N-tosylaminomethyl-substituted fluorenes in one pot. Moreover, fluorenes are synthesized via tandem Cu-catalyzed [3 + 2] cycloaddition and Rh-catalyzed denitrogenative cyclization in a 5-exo mode starting from 2-ethynylbiaryls and N-sulfonyl azides in one pot.

Synthesis of ethoxy dibenzooxaphosphorin oxides through palladium-catalyzed C(sp(2))-H activation/C-O formation.

We report an efficient Pd-catalyzed C(sp(2))-H activation/C-O bond formation for the synthesis of ethoxy dibenzooxaphosphorin oxides from 2-(aryl)arylphosphonic acid monoethyl esters under aerobic conditions.

Phosphaannulation by palladium-catalyzed carbonylation of C-H bonds of phosphonic and phosphinic acids.

An efficient phosphaannulation by Pd-catalyzed carbonylation of C-H bonds of phosphonic and phosphinic acids for the synthesis of oxaphosphorinanone oxides is reported. These compounds are novel phosphorus heterocyclic scaffolds, thus opening a new avenue to sequential C-C/C-O bond formation in one pot.

Synthesis of 2-aryl-2H-benzotrizoles from azobenzenes and N-sulfonyl azides through sequential rhodium-catalyzed amidation and oxidation in one pot.

An efficient synthetic method of 2-aryl-2H-benzotriazoles from nonprefunctionalized azobenzenes and N-sulfonyl azides via sequential Rh-catalyzed amidation (C-N bond formation) and oxidation (N-N bond formation) with PhI(OAc)2 in one pot is reported.