تفاعل #6645

معادلة التفاعل

diethylchlorophosphate

diisopropylamine

n-butyl lithium

2,2,4,4-tetramethyl-6-acetylchroman

Compound 85

2,2,4,4-tetramethyl-6-acetylchroman

lithium diisopropylamide

n-butyl lithium

diisopropylamine

→

title compound

2,2,4,4-Tetramethyl-6-ethynyl-chroman

المذيبات

hexane

hexane

THF

THF

THF

ظروف التفاعل

المعالجة

1. 1
   workup.ADDITIONwas added slowly, under nitrogen
2. 2
   workup.STIRRINGThe mixture was stirred at -78 degrees C
3. 3
   workup.WAITfor a further 1 h
4. 4
   درجة الحرارةto warm to room temperature
5. 5
   أخرىThe cooling bath was removed
6. 6
   workup.STIRRINGthe mixture was stirred at room temperature for 16 h
7. 7
   workup.ADDITIONThe mixture was then treated with 10 ml of ice water
8. 8
   أخرىThe organic layer was separated
9. 9
   استخلاصthe aqueous layer was extracted with 3×30 ml of pentane
10. 10
    غسيلwashed successively with 2.30 ml of dilute HCl, water, 3×30 ml of saturated NaHCO3 solution and saturated NaCl solution
11. 11
    تجفيفdried (MgSO4)
12. 12
    أخرىThe solvent was removed in vacuo
13. 13
    أخرىthe residue was purified by flash chromatography (silica; 2% ethyl acetate in hexane)

الإجراء التجريبي

To a cooled (-78 degrees C.) solution of 522 mg (5.17 mmol) of diisopropylamine in 8 ml of dry THF was added slowly, under nitrogen, 3.23 ml of 1.6 M (5.17 mmol) n-butyl lithium in hexane. The mixture was stirred at -78 degrees C. for 40 minutes and then treated with a solution of 1.24 g (5.17 mmol) of 2,2,4,4-tetramethyl-6-acetylchroman (Compound 85) in 2 ml of dry THF. The mixture was stirred at -78 degrees C. for a further 1 h and then treated with 895 mg (5.19 mmol) of diethylchlorophosphate. The reaction mixture was allowed to warm to room temperature and transferred by double-ended needle into a solution of lithium diisopropylamide in THF at -78 degrees C. [prepared as described above from 1.04 g (10.34 mmol) of diisopropylamine and 6.46 ml of 1.6 M (10.34 mmol) n-butyl lithium in hexane]. The cooling bath was removed and the mixture was stirred at room temperature for 16 h. The mixture was then treated with 10 ml of ice water and acidified to a pH of 2 with 10% HCl. The organic layer was separated and the aqueous layer was extracted with 3×30 ml of pentane. The organic extracts were combined and washed successively with 2.30 ml of dilute HCl, water, 3×30 ml of saturated NaHCO3 solution and saturated NaCl solution and then dried (MgSO4). The solvent was removed in vacuo and the residue was purified by flash chromatography (silica; 2% ethyl acetate in hexane) to give the title compound as a pale yellow oil. PMR (CDCl3): δ 1.31 (6H, s), 1.32 (6H, s), 1.50 (2H, s), 3.00 (1H, s), 6.72 (1H, d, J~8.4 Hz), 7.20 (1H, dd, J~8.4 Hz, 2.1 Hz), 7.42 (1H, d, J~ 2.1 Hz). MS exact mass, m/e 214.1251 (calcd. for C15H18O, 214.1357).

المصدر