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. Issue 43 (14th October 2020)

• Record Type: Journal Article
• Authors: Tyagi, Akshi; Reshi, Noor U Din; Daw, Prosenjit; Bera, Jitendra K.
• Is Part Of: Dalton transactions. Volume 49:Issue 43(2020)
• Page Start: 15238
• Page End: 15248
• Publication Date: 2020-10-14
• Subjects: Chemistry, Inorganic -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/d0dt02918a
• Languages: English
• ISSNs: 1477-9226

Abstract

Abstract : A Pd(ii ) complex containing a mesoionic carbene and phosphine ligands is an efficient catalyst for tandem coupling/cyclization reaction. Abstract : 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.