反应详情

温度

0 °C

Under a static nitrogen atmosphere at 0° C., a solution of n-butyllithium (8 g, 0.125 mol) in hexane was added to a solution of tetramethylethylenediamine (14.3 g, 0.123 mol) in 30 ml. of anhydrous cyclohexane with constant stirring. While maintaining the temperature at 0° C., a solution of N-ethylbenzylamine (8.1 g, 0.06 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 3 hours at 26° C. and then cooled to -71° C. using a solid carbon dioxide-acetone bath. A solution of phenylphosphonic dichloride (12.5 g, 0.064 mol) in 30 ml. of anhydrous cyclohexane was rapidly added to the suspension causing the temperature of the reaction to increase to -20° C. When the reaction temperature began to decrease, the solid carbon dioxide-acetone bath was removed and the reaction mixture was stirred for 2 hours. The reaction mixture was cooled to 0° C. and then quenched with the rapid addition of 12 ml. of acetic acid. After stirring for 10 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 washed with brine, dried over magnesium sulfate and concentrated in vacuo to yield an orange oil. This oil was distilled at 170° C. and 0.2 torr, yielding a yellow oil which was then slurried in diethyl ether to yield a white solid. The white solid was purified on a silica gel column using ethyl acetate as the eluant. Fractions containing the benzazaphosphole were combined and concentrated in vacuo to produce a crude product. The crude product was slurried in ether to yield 1-phenyl-2-ethyl-2,3-dihydro-1H-2,1-benzazaphosphole-1-oxide as a crystalline precipitate. A second crop was obtained from the ether filtrate and the combined product yield was recrystallized from methylcyclohexane to yield 1-phenyl-2-ethyl-2,3-dihydro-1H-2,1-benzazaphosphole-1-oxide (1.3 g, 8% yield) as white crystals having a melting point of 94°-95° C. and the following analysis:

1. customto produce a suspension
2. temperaturecooled to -71° C.
3. customthe temperature of the reaction
4. temperatureto increase to -20° C
5. customthe solid carbon dioxide-acetone bath was removed
6. stirringthe reaction mixture was stirred for 2 hours
7. temperatureThe reaction mixture was cooled to 0° C.
8. customquenched with the rapid addition of 12 ml
9. stirringAfter stirring for 10 minutes
10. customthe cyclohexane was removed on a rotary evaporator
11. customthe resulting residue was partitioned between methylene chloride and water
12. customThe layers were separated
13. washthe methylene chloride layer was washed with brine
14. dry with materialdried over magnesium sulfate
15. concentrationconcentrated in vacuo
16. customto yield an orange oil
17. distillationThis oil was distilled at 170° C.
18. custom0.2 torr, yielding a yellow oil which
19. customto yield a white solid
20. customThe white solid was purified on a silica gel column
21. additionFractions containing the benzazaphosphole
22. concentrationconcentrated in vacuo
23. customto produce a crude product