The synthesis and structure of gemini QASs of 1,4:3,6-dianhydro-l-iditol

• Gemini quaternary ammonium salts of 1,4:3,6-dianhydro-l-iditol were synthesized.
• Structural analysis was made based on NMR and X-ray diffraction.
• Conformational analysis of 1,4:3,6-dianhydrohexitol residue was performed.
• Syntheses under mild conditions with O-triflyl leaving group gave excellent yields.

New, efficient, straightforward method of synthesizing quaternary diammonium salts of 1,4:3,6-dianhydro-l-iditol have been developed. This paper presents the synthesis and structural analysis of diammonium (gemini) salts, including their X-ray diffraction analysis, wherein the linking structure of nitrogen atoms consists of two fused furanoid rings. 1,4:3,6-dianhydro-2,5-di-O-triflyl-d-mannitol and four tertiary amines, i.e., 4-(N,N-dimethylamino)pyridine (DMAP), pyridine, trimethylamine and N,N-dimethyloctylamine, were used for the synthesis. All the syntheses were carried out under mild conditions by the direct nucleophilic displacement of the O-triflil group by the amine. Walden inversion of configuration at C2 and C5 atoms has occurred during the reaction, giving products with l-ido configuration. Furthermore, NMR and X-ray conformational analysis of 1,4:3,6-dianhydrohexitol residue was done. In most cases furanoid rings adopt the twisted conformation both in the crystal and in solution.

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