N,N,N',N'-Tetramethylethylenediamine → 1-Trityl-5-bromo-1,2,4-triazole

Participants

Reaction Conditions

Reaction Steps

A stirred solution of 1-trityl-1,2,4-triazole (15.55 g, prepared as described in Example 1) and N,N,N',N'-tetramethylethylenediamine (5.8 g) in dry tetrahydrofuran (500 ml) was cooled to -70° C. under nitrogen and treated dropwise with n-butyllithium (37.5 ml, 1.6M in hexane). The deep-red solution was stirred at -70° C. for twenty minutes, then treated dropwise with a solution of bromine (10.4 g) in dry tetrahydrofuran (10 ml). The now brownish-yellow solution was allowed to warm to -20° C., quenched with 0.1M sodium thiosulphate solution (150 ml), and extracted with dichloromethane (500 ml). The organic layer was washed with water (4×100 ml), dried and evaporated. The residue was chromatographed on silica, using dichloromethane-ether (25:2) as eluant, to give 1-trityl-5-bromo-1,2,4-triazole (7.86 g, m.p. 239°-241° C.). NMR (CDCl3):δ7.1-7.3(15H,m), 7.95(1H,s).

Provenance & Evidence