An efficient copper‐catalyzed protocol has been developed for the synthesis of carbamates from dialkylformamides and phenols possessing directing groups such as benzothiazole, quinoline and formyl at the ortho‐position. In this chelation assisted approach, CO bond formation takes place via a cross dehydrogenative coupling (CDC) between the formyl CH of dialkylformamide and phenolic OH in the presence of copper(II)acetate/aqueous tert‐butyl hydroperoxide. Under identical reaction conditions, salicylic acid derivatives underwent amidation with the carboxylic group rather than formamidation of the phenolic OH. The use of a cheap and environmentally benign catalyst along with the tolerance of a wide range of functional groups makes this an easy, phosgene‐free route to carbamates.magnified image

CuO nanoparticle catalyzed synthesis of 2,3-disubstituted quinazolinones has been accomplished from 2-halobenzamides and (aryl)methanamines under an air atmosphere. This synthesis of the N-heterocycle involves a sequential Ullmann coupling [between 2halobenzamide and (aryl)methanamine], oxidation of the in situ generated secondary amine to imine. This is then followed by an intramolecular nucleophilic attack of the amidic N−H on to the imine carbon (C−N bond formation) resulting in the synthesis of 2,3disubstituted quinazolinones. The recyclability of the catalyst and tolerance of a wide range of functional groups makes this method efficient and cost-effective.

Substrate-directed ortho C-H amination of azoarenes using TMSN3 as the source of nitrogen leading to the synthesis of 2-aryl-2H-benzotriazoles has been accomplished with the help of Pd/TBHP combinations. An intermolecular o-azidation (C-N bond formation) followed by an intramolecular N-N bond formation via nucleophilic attack of one of the azo nitrogen onto the o-azide nitrogen leads to cyclization with the expulsion of N2.

Ac opper(II)-catalyzed oxidative methylene-bridged dimerizationo ft wo analogousi midazo[1,2-a]pyridines has been achieved using N,N-dimethylacetamide (DMA)a ss olvent cum methylene source.T hisr eactionw orks with av ariety of substituted imidazo[1,2-a]pyridines giving theirp roductsi n moderate to good yields. Isotopic labellinge xperiments revealed that the methylene group in the product originates from the N,N-dimethyl moiety of DMA.

tert-Butyl nitrite serves the dual role of an oxidant as well as a N1 synthon in a multicomponent reaction involving quinolines, isoquinolines, and styrenes. Herein, two sp C-H functionalizations of styrenes and one sp C-H functionalization of quinolines and isoquinolines lead to the formation of fused quinolines and isoquinolines via three sequential C-N bond formations.

A regioselective and concomitant transfer of thiocyanate (-SCN) and aroyl/acyl (-COR) groups from aroyl/acyl isothiocyanates onto oxiranes was achieved, giving thiocyanato benzoates in 100% atom economy. In this biomimetic organocatalytic process, one part (-SCN) of aroyl/acyl isothiocyanates acts as the nucleophile whereas the other half (-COR) serves as an electrophilic partner.

A base-promoted synthesis of quinoline-4(1H)-thiones has been accomplished from the in situ generated o-alkynylthiourea, obtained by reacting o-alkynylanilines with aroyl/acyl isothiocyanates. A 6-exo-dig S-cyclization of the in situ generated thiourea is followed by a rearrangement to give quinoline-4(1H)-thiones.

A metal free synthesis of 3-aroylindole involving two sp(3) C-H activation has been achieved starting from o-alkynyl-N,N-dialkylamines using catalyst TBAI and oxidant TBHP.