Regiochemistry of nucleophilic substitution of pentachloropyridine with N and O bidentate nucleophiles

Abstract

Site reactivity of some enol-imines derived from N-aryl formamides with pentachloropyridine under basic conditions in dry CH 3 CN was investigated. The aromatic nucleophilic substitution of pentachloropyridine with enol-imines occurs at the 4-position of pyridine ring by both oxygen and nitrogen site of enol-imines.Nucleophilic attack by the oxygen of enol-imine gave corresponding oximino compounds as a mixture of E-and Z-isomers. In contrast, nucleophilic attack by the nitrogen of enol-imine gave the unexpected N,Ndi-substituted aryl compounds. The structures of all the compounds were confirmed by IR, 1 H NMR, 13 C NMR and 19 F NMR spectroscopy as well as elemental analysis and X-ray crystallography. Results and discussion Synthesis of precursor formamide compoundsSeveral papers have reported the preparation of these important compounds. [30][31][32] In this paper, we have established a new method for the synthesis of these compounds in a very short reaction time with high yields. The reaction of the aromatic

Direct Synthesis of Trichloro‐thiazolo[3,2‐a]pyrimidine and Thiazolo[2,3‐b]quinazoline Derivatives

“…Reaction pentachloropyridine with (benzylidene)‐4‐(2‐aryl)‐3,4,5,6,7,8‐hexahydroquinazoline‐2(1 H )‐thione/(benzylidene)‐4‐(2‐aryl)‐3,4,6,7‐tetrahydro‐1 H ‐cyclopenta[ d ]pyrimidine‐2(5 H ) thione affords the intermediate thioether A , which, on intermolecular cyclization, followed by the nucleophilic attack of nitrogen atom of pyrimidinethiones on electrophilic chlorine of 2 , affords the title compounds .…”