40485-03-8Relevant articles and documents
Palladium complexes with an annellated mesoionic carbene (MIC) ligand: Catalytic sequential Sonogashira coupling/cyclization reaction for one-pot synthesis of benzofuran, indole, isocoumarin and isoquinolone derivatives
Bera, Jitendra K.,Daw, Prosenjit,Reshi, Noor U Din,Tyagi, Akshi
supporting information, p. 15238 - 15248 (2020/11/18)
Two Pd(ii) complexes (1 and 2) featuring a fused π-conjugated imidazo[1,2-a][1,8]naphthyridine-based mesoionic carbene ligand have been synthesized and structurally characterized. Both complexes effectively catalyze the one-pot synthesis of benzofuran starting from phenylacetylene and 2-iodophenol under mild conditions. Complex 1 is found to be an excellent catalyst for the straightforward access to a library of benzofuran, indole, isocoumarin and isoquinolone derivatives by the reaction of terminal alkynes with 2-iodo derivates of phenol, N-methyl aniline, benzoic acid and N-methyl benzamide, respectively. The general utility of the catalytic method is demonstrated using a variety of diversely substituted terminal alkynes and the corresponding desired products are obtained in good to excellent yields. On the basis of control experiments, a two-cycle mechanism is proposed which involves the Sonogashira coupling of 2-iodo derivatives with alkynes and the subsequent cyclization of the corresponding 2-alkynyl compounds.
One-pot synthesis of substituted benzo[b]furans from mono- and dichlorophenols using palladium catalysts bearing dihydroxyterphenylphosphine
Yamaguchi, Miyuki,Katsumata, Haruka,Manabe, Kei
, p. 9270 - 9281 (2013/10/08)
A dihydroxyterphenylphosphine bearing cyclohexyl groups on the phosphorus atom (Cy-DHTP) was found to be a powerful ligand for the palladium-catalyzed one-pot synthesis of substituted benzo[b]furans from 2-chlorophenols and terminal alkynes. This catalyst
Synthesis of 2-substituted benzofurans and indoles using functionalized titanium benzylidene reagents on solid phase
Macleod, Calum,McKiernan, Gordon J.,Guthrie, Emma J.,Farrugia, Louis J.,Hamprecht, Dieter W.,Macritchie, Jackie,Hartley, Richard C.
, p. 387 - 401 (2007/10/03)
Titanium(IV) benzylidenes bearing a masked oxygen or nitrogen nucleophile in the ortho position were generated from thioacetals, using low-valent titanocene complex, Cp2Ti[P(OEt)3]2. Methylene acetal, alkyl ether, silyl ether, fluoro, tertiary amino, and N-alkyl, N-benzyl, N-prenyl, and N-silyl tert-butyl carbamate groups were tolerated in the titanium alkylidene reagents (Schrock carbenes). Aryl-chlorine bonds were stable to the titanium benzylidene functionality, but there was poor chemoselectivity for the reduction of the thioacetal in the presence of an aryl chloride. The titanium benzylidenes converted Merrifield and Wang resin-bound esters into enol ethers. The oxygen nucleophile was masked as a TMS ether, and when the resin-bound enol ethers bearing this ortho substituent were treated with 1% TFA in dichloromethane, benzofurans were released from resin in high yields. The chameleon catch strategy ensured excellent purity. In a similar way, N-alkylated and N-silylated tert-butyl carbamates were used for the synthesis of N-alkyl and N-Boc indoles, respectively. These traceless solid-phase syntheses of heterocycles are believed to involve post-cleavage modification rather than cyclative termination.
