Reaction #2460287

Reaction equation

1,3-dicyclohexylcarbodiimide

2-butynoic acid

9-fluorenemethanol

dimethylamino-pyridine-p-toluenesulfonic acid salt

→

9-fluorenylmethyl 2-butynoate

Yield 55.3%

Solvents

dichloromethane

Conditions

Workup

1. 1
   OtherFirst, 9-fluorenylmethyl 2-butynoate was prepared
2. 2
   Temperaturethe reaction mixture was warmed to ambient and
3. 3
   FiltrationThe urea by product was filtered
4. 4
   Washthe filtrate was washed successively with 10% aqueous HCl, 10% aqueous NaHCO3, water, and brine
5. 5
   DryingThe solution was dried (Na2SO4)
6. 6
   Concentrationconcentrated
7. 7
   OtherThe product was purified by column chromatography

Procedure

First, 9-fluorenylmethyl 2-butynoate was prepared. A mixture of 2-butynoic acid (11.6 g, 138 mmol), 9-fluorenemethanol (35.2 g, 179 mmol), dimethylamino-pyridine-p-toluenesulfonic acid salt (16.3 g, 55 mmol), and anhydrous dichloromethane (210 mL) was cooled to 0° C. under nitrogen, and 1,3-dicyclohexylcarbodiimide (34.2 g, 166 mmol) was added. After 15 min, the reaction mixture was warmed to ambient and stirred for 12 h. The urea by product was filtered, and the filtrate was washed successively with 10% aqueous HCl, 10% aqueous NaHCO3, water, and brine. The solution was dried (Na2SO4) and concentrated to deposit a yellow oil. The product was purified by column chromatography to provide 20.0 g (54% of theory) of 9-fluorenylmethyl 2-butynoate as a yellow-green solid. 1H NMR (CDCl3): δ 1.98 (s, 3H), 4.20 (m, 1H), 4.45 (d, 2H), 7.32 (m, 4H), 7.60 (d, 2H), 7.70 (d, 2H).

Source