title: An alternative synthesis of 2-(N-arylhydrazono)-1-benzothiophen-3-ones.
abstract: In the presence of triethylamine, 2-mercaptobenzoic acid readily adds onto acylhydrazonoyl chlorides (1a-c) (precursors of the reactive nitrile imine 1,3-dipolar species) to afford good yields of the corresponding 2-[(2-oxo-1-arylhydrazonopropan-1-yl)mercapto]benzoic acids (2a-c). The latter acyclic adducts, in THF in the presence of 1,1'-carbonyldiimidazole, undergo intramolecular cyclization involving the activated carboxy and the enol functionality to deliver the respective 2-(N-arylhydrazono)-3-oxobenzothiophenes (3a-c). In the solid state, the latter compounds adopt the (Z)-geometry around the C=N double bond as evidenced by single crystal X-ray structure determination for 3b.
authors.affiliation: Chemistry Department, Faculty of Science, University of Jordan, Amman-Jordan.
authors.forename: Jalal A
authors.initials: JA
authors.lastname: Zahra
authors.forename: Bassam A
authors.initials: BA
authors.lastname: Abu Thaher
authors.forename: Mustafa M
authors.initials: MM
authors.lastname: el-Abadelah
authors.forename: Roland
authors.initials: R
authors.lastname: Boese