Diazo compounds and N-tosylhydrazones: novel cross-coupling partners in transition-metal-catalyzed reactions

Unprecedented synthesis of aza-bridged benzodioxepine derivatives through a tandem Rh(ii)-catalyzed 1,3-rearrangement/[3+2] cycloaddition of carbonyltriazoles

Rh(ii)-catalyzed novel tandem intramolecular cycloisomerizations of aldehydes or ketones with 1-sulfonyl 1,2,3-triazoles have been disclosed, providing a facile protocol to access a series of functionalized aza-bridged benzodioxepine heterocycles.

Palladium and copper-catalyzed ligand-free coupling of phenylhydrazines in water

An efficient methodology for the synthesis of biaryls via Pd/Cu catalyzed coupling of unprotected phenylhydrazines in water is reported.

Palladium-catalyzed three-component reaction of N-tosylhydrazone, norbornene and aryl halide

A palladium-catalyzed three-component reaction that involves an intermolecular Heck-type reaction and alkyl palladium carbene migratory insertion has been demonstrated.

A Pd-catalyzed cascade reaction of N–H insertion and oxidative dehydrogenative aromatization: a new entry to 2-amino-phenols

A palladium-catalyzed cascade reaction of N–H insertion and oxidative dehydrogenative aromatization under an air atmosphere has been developed under relatively mild conditions.

Synthesis of 1H-indazoles from N-tosylhydrazones and nitroaromatic compounds

1H-Indazoles have been synthesized from readily available N-tosylhydrazones and nitroaromatic compounds under mild reaction conditions.

Synthesis of benzo-γ-sultams via the Rh-catalyzed aromatic C–H functionalization of diazosulfonamides

Diazosulfonamides are first introduced and employed to synthesize 1-aryl-benzo-γ-sultams via Rh-catalyzed intramolecular aromatic C–H functionalization.

Pd-Catalyzed ring-opening cross-coupling of cyclopropenes with aryl iodides

A palladium-catalyzed cross-coupling reaction of cyclopropenes with aryl iodides affords 1,3-butadiene products in good yields.

Palladium catalyzed N–H bond insertion and intramolecular cyclization cascade: the divergent synthesis of heterocyclics

A palladium-catalyzed one-pot procedure of N–H insertion and Heck cyclization/base promoted cyclization has been developed.

Investigation into the reactivity of 16-electron complexes Cp#Co(S2C2B10H10) (Cp# = Cp, Cp*) towards methyl diazoacetate and toluenesulphonyl azide

A three-component reaction of the 16-electron half-sandwich complex Cp*Co(S₂C₂B₁₀H₁₀) (2) with both methyl diazoacetate (MDA) and toluenesulphonyl azide (TsN₃) led to the formation of complexes 3 and 4, while a two-component reaction of complex 2 with MDA afforded products 5–7.

Deciphering the origin of cooperative catalysis by dirhodium acetate and chiral spiro phosphoric acid in an asymmetric amination reaction

The transition state for enantioselective protonation by chiral phosphoric acid enjoys a cooperative stabilization offered by the dirhodium catalyst.

CuI-catalyzed cross-coupling of terminal alkynes with dialkoxycarbenes: a general method for the synthesis of unsymmetrical propargylic acetals

A general source of dialkoxycarbenes, 2,2-dialkoxy-5,5-dimethyl-Δ³-1,3,4-oxadiazolines, have been successfully employed as coupling partners in CuI-catalyzed cross-coupling reactions with terminal alkynes, which afforded various unsymmetrical propargylic acetals in good yields.

Formal carbon insertion of N-tosylhydrazone into B-B and B-Si bonds: gem-diborylation and gem-silylborylation of sp3 carbon

A convenient method is developed to synthesize 1,1-diboronates from the corresponding N-tosylhydrazones. This method is also applicable to synthesize 1-silyl-1-boron compounds. Meanwhile, derivatization and consecutive Pd-catalyzed cross-coupling reactions with 1,1-boronates were explored, demonstrating the synthetic potential of 1,1-diboronates.

Conversion of azides into diazo compounds in water

Diazo compounds are in widespread use in synthetic organic chemistry but have untapped potential in chemical biology. We report on the design and optimization of a phosphinoester that mediates the efficient conversion of azides into diazo compounds in phosphate buffer at neutral pH and room temperature. High yields are maintained in the presence of common nucleophilic or electrophilic functional groups, and reaction progress can be monitored by colorimetry. As azido groups are easy to install and maintain in biopolymers or their ligands, this new mode of azide reactivity could have substantial utility in chemical biology.

Base-catalyzed synthesis of substituted indazoles under mild, transition-metal-free conditions

Back to basics: A transition-metal-free method developed for the synthesis of indazoles involves an inexpensive catalytic system composed of a diamine and K2CO3. Various (Z)-2-bromoacetophenone tosylhydrazones were converted into indazoles at room temperature in excellent yields (see example; Ts = p-toluenesulfonyl). The yield was improved by photoisomerization with UV light when E/Z isomeric mixtures of the starting material were used.