N,N,N',N'-Tetramethylethylenediamine → 1-phenyl-2-trimethylsilyl-2,3-dihydro-1H-2,1-benzazaphosphole-1-oxide

Participants

Reaction Conditions

Reaction Steps

Under a static nitrogen atmosphere at 0° C., a solution of n-butyllithium (16 g, 0.25 mol) in hexane was added to a solution of tetramethylethylenediamine (28.6 g, 0.246 mol) in 120 ml. of anhydrous cyclohexane with constant stirring. While maintaining the temperature of the reaction at 0° C., a solution of N-trimethylsilylbenzylamine (21.6 g, 0.12 mol) in 60 ml. of anhydrous cyclohexane was added to the reaction mixture to produce a suspension containing a dilithio compound. This suspension was stirred for 16 hours at 26° C. and then cooled to -76° C. using a solid carbon dioxide-acetone bath. A solution of phenylphosphonic dichloride (25 g, 0.128 mol) in 120 ml. of anhydrous cyclohexane was rapidly added to the suspension causing the temperature of the reaction to increase to -15° C. The reaction mixture was allowed to cool to -76° C., after which time the solid carbon dioxide-acetone bath was removed and the reaction mixture was stirred for 3 hours. The reaction mixture was cooled to 0° C., then quenched with the rapid addition of 24 ml. of acetic acid. After stirring the reaction mixture for 5 minutes, the cyclohexane was removed on a rotary evaporator, and the resulting residue was partitioned between methylene chloride and water. The layers were separated and the methylene chloride layer was dried over magnesium sulfate and concentrated in vacuo to yield an oil. Distillation of this oil at 180° C. and 0.3 mm yielded 1-phenyl-2-trimethylsilyl-2,3-dihydro-1H-2,1-benzazaphosphole-1-oxide.

Provenance & Evidence