N,N,N',N'-Tetramethylethylenediamine → 1-phenyl-2-(4-methylphenyl)-2,3-dihydro-1H-2,1-benzazaphosphole-1-oxide

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Reaction Conditions

Reaction Steps

Under a static nitrogen atmosphere at 0° C., a solution of n-butyllithium (3.9 g, 0.061 mol) in hexane was added to a solution of tetramethylethylenediamine (1.8 g, 0.0155 mol) in 30 ml. of anhydrous cyclohexane with constant stirring. While maintaining the temperature of the reaction at 0° C., a solution of N-benzyl-4-toluidine (5.9 g, 0.03 mol) in 30 ml. of anhydrous cyclohexane was added to the reaction mixture to produce a suspension containing a dilithio compound. The suspension containing the dilithio compound was stirred for 4 hours at 26° C. and then cooled to 0° C. A solution of phenylphosphonic dichloride (6.25 g, 0.032 mol) in 30 ml. of anhydrous cyclohexane was added dropwise to the suspension and the resulting mixture was stirred for 1.5 hours at 26° C. The reaction was quenched with the rapid addition of 6 ml. of acetic acid. The mixture was concentrated in vacuo and the resulting residue partitioned in methylene chloride and water. The layers were separated and the methylene chloride layer was washed with 5% hydrochloric acid, then water, dried over sodium sulfate and concentrated in vacuo to yield a brown-green glass. The brown-green glass was crystallized from ethyl acetate to yield light green plates which were recrystallized from toluene to yield 1-phenyl-2-(4-methylphenyl)-2,3-dihydro-1H-2,1-benzazaphosphole-1-oxide (1.9 g, 20% yield) as white crystals having a melting point of 197°-199° C. and the following analysis:

Provenance & Evidence