In situ generation of 2,3-diaryltetrazolinylidenes: trapping experiments and ring opening to 1-cyanoazimines

Abstract

transferred to a separatory funnel containing brine (10 mL). The mixture was extracted with chloroform (6X10 mL), and then the combined extracts were dried over MgSQ4. The solvent was evaporated and the residue was purified by reverse-phase chromatography (Water Delta Prep, 30 cm X 30 mm Clg Delta Pak column, 80% water/methanol to 40% water/methanol over 10 min, 40% water/methanol to 100% methanol over 15 min) to provide syn oxime 28 (10 mg, 6% yield) and the desired anti oxime 29 (82 mg, 53% yield) as colorless oils: 'H NMR (200

Organometallic Tetrazole Derivatives: Preparation and Application to Organic Synthesis

“…This fragmantaion path was recently confirmed by obtaining N,N-disubstituted cyanamide 19 at successive treatment of 1-benzyloxymethyltetrazole with butyllithium and benzyl bromide at -78°C in THF in the presence of N,N-dimethyltetrahydropyrimidin-2-one [24]. 5-Lithio-2,3-diaryltetrazolium salts 6 obtained at -78°C at warming to room temperature suffered the opening of the tetrazole ring to furnish 2,3-diaryl-1-cyanoazimines in 63-85% yields [26,27].…”

“…The process is commonly carried out in THF, more seldom in ethyl ethter, and sometimes in the presence of N,N,N',N'-tetramethylethylenediamine (TMEDA). In this way series of 5-lithio-1 -R -t e t r a z o l e s 4 ( R = M e [ 1 0 ] , B z [ 2 0 , 2 1 ] , 4-MeOC 6 H 4 CH 2 [21], BzOCH 2 [22]), 5-lithio-2-Rtetrazoles 5 (R = Me 3 SiCH 2 CH 2 OCH 2 [23], BzOCH 2 [24], azabicycloalkyl [25]), and 5-lithio-2,3-diaryltetrazolium salts 6 [26,27] were prepared. In view of the high reactivity these compounds were not isolated as individual substances but were applied to further reactions in solution.…”

Recent advances in neutral and anionic N-heterocyclic carbene – betaine interconversions. Synthesis, characterization, and applications

“…41 Tetrazoliumsulfonate 41, the azimine 43, tetrazolium-olate 44, and a dimerized thiolate connected by an S-S bond, were obtained. The betaines 43 and 44 were formed by extrusion of SO 2 from tetrazoliumsulfinate 40 via the NHC 42.…”

Fluorinated Triazoles and Tetrazoles

“…Cesium fl uoride was also used in the synthesis of 2,3-di( p -tolyl)-5-fl uorotetrazolium bromide 25 from the corresponding 5-triphenylphosphoniotet razolium salt [ 33 ]. …”