Reacción #340382

Ecuación de reacción

NH4Cl

LDA

heptane THF ethylbenzene

7-methoxy-isothiochroman-4-one

HMPA

methyl cyanoformate

→

7-methoxy-isothiochroman-4-one-3-carboxylic acid methyl ester

Rendimiento 78.7%

Disolventes

THF

Condiciones de reacción

Tratamiento posterior

1. 1
   Temperaturato warm to room temperature
2. 2
   ExtracciónThe slurry was extracted with EtOAc (3×75 mL)
3. 3
   Secadodried (MgSO4)
4. 4
   Concentraciónconcentrated under reduced pressure
5. 5
   Otroto provide a bright yellow oil
6. 6
   OtroThe oil was purified on silica using medium pressure chromatography (9:1 petroleum ether/EtOAc)

Procedimiento

A 2.0 M solution of LDA in heptane/THF/ethylbenzene (1.61 mL, 3.21 mmol) was added in a dropwise manner to a solution of 7-methoxy-isothiochroman-4-one (0.50 g, 2.57 mmol) in THF (50 mL) at −78° C. under N2. After 30 min at −78° C. HMPA (0.46 g, 2.57 mmol) and methyl cyanoformate (0.27 g, 3.21 mmol) were added and the yellow solution was allowed to stir at −78° C. for 30 min. The solution was then allowed to warm to room temperature and a saturated solution of NH4Cl (100 mL) was added. The slurry was extracted with EtOAc (3×75 mL) and the organic extracts were combined, dried (MgSO4) and concentrated under reduced pressure to provide a bright yellow oil. The oil was purified on silica using medium pressure chromatography (9:1 petroleum ether/EtOAc) to provide 7-methoxy-isothiochroman-4-one-3-carboxylic acid methyl ester as a bright yellow oil (0.51 g, 78%). 1H-NMR (300 MHz, CDCl3) δ 3.73 (s, 2H), 3.83 (s, 3H), 3.85 (s, 3H), 6.67 (d, J=3 Hz, 1H), 6.45 (dd, J=3, 8.7 Hz, 1H), 7.80 (d, J=8.7 Hz, 1H), 12.52 (s, 1H).

Fuente