Reactions of Arylthiazylamides with Internal and External Fluoro Electrophiles − Formation of Products with Unusual Structures

Abstract

The heteroatom reactivity of the title anions [as (Me2N)3S+ and Cs+ salts] toward both internal and external fluoro electrophiles has been investigated. The intramolecular nucleophilic cyclization of [ArNSN]− (as the cesium salts) bearing at least one ortho fluorine afforded 2,1,3-benzothiadiazoles (e.g. 2a,b), whereas intermolecular condensation with polyfluorinated pyridine and naphthalene afforded Ar−N=S=N−R with R = 4-PyF (4) and R = 2-NpF (8). Further interaction of [ArNSN]− with 4 or 8 proceeded with the transfer of NSN units resulting in (ArN=)2S (5) and [RNSN]−, followed by decomposition (R = 4-PyF) to 4-PyFNH2 (6) or intramolecular cyclization (R = 2-NpF) to the polyfluorinated thiadiazole 9. The compounds of types 4, 5, 8, and 9 have been characterized by single-crystal X-ray diffraction as having both Z,E and Z,Z configurations [8 and 9 as molecular complexes with C10F8 and (Ph−N=)2S (5e), respectively, featuring π-stacking interactions of the arene−polyfluoroarene type]. Besides normal aryl−polyfluoroaryl interactions, the 8·C10F8 complex also displays unusual polyfluoroaryl−polyfluoroaryl π-stacking.