Valentin A. Rassadin

Facile Gold-Catalyzed Heterocyclization of Terminal Alkynes and Cyanamides Leading to Substituted 2-Amino-1,3-Oxazoles

Facile gold-catalyzed heterocyclization based upon intermolecular trapping of the generated α-oxo gold carbenes with various cyanamides R(2)R(3)NCN (R(2)/R(3) = Alk/Alk, -(CH2)2O(CH2)2-, Ar/Ar, Ar/H) has been developed. In most cases, 2-amino-1,3-oxazoles functionalized at the nitrogen atom as well as at the fifth position of the heterocyclic ring (12 examples) were isolated in good to moderate yields.

Methods of Sultam Synthesis

Methods for preparing mono- and polycyclic sultams are systematically reviewed.

Solvent- and halide-free synthesis of pyridine-2-yl substituted ureas through facile C–H functionalization of pyridine N-oxides

A novel solvent- and halide-free atom-economical synthesis of practically useful pyridine-2-yl substituted ureas utilizes easily accessible or commercially available pyridine N-oxides (PyO) and dialkylcyanamides. The observed C–H functionalization of PyO is suitable for the good-to-high yielding synthesis of a wide range of pyridine-2-yl substituted ureas featuring electron donating and electron withdrawing, sensitive, or even fugitive functional groups at any position of the pyridine ring (63–92%; 19 examples). In the cases of 3-substituted PyO, the C–H functionalization occurs regioselectively providing a route for facile generation of ureas bearing a 5-substituted pyridine-2-yl moiety.

Synthesis of benzannelated sultams by intramolecular Pd-catalyzed arylation of tertiary sulfonamides

A new and efficient approach to five- and six-membered benzannelated sultams by intramolecular C-arylation of tertiary 1-(methoxycarbonyl)methanesulfonamides under palladium catalysis is described. In case of the α-toluenesulfonamide derivative, an unexpected formation of a 2,3-diarylindole was observed under the same conditions.

Gold-Catalyzed Hydrohydrazidation of Terminal Alkynes

Facile gold-catalyzed hydrohydrazidation of alkynes with various hydrazides R2CONHNH2 (R = Alk or Ar; including those with an additional nucleophilic moiety) in the presence of Ph3PAuNTf2 (6 mol %) leading to a wide range of substituted keto- N-acylhydrazones (18 examples) in excellent to good yields (99-66%) is reported. This novel metal-catalyzed coupling proceeds under mild conditions (chlorobenzene, 60 °C), exhibits high functional group tolerance, and is insensitive to the electronic and steric effects of the substituents in the reactants.