230642-84-9

4-Vinyl-2,3-dihydrobenzofuran is an intermediate in the synthesis of tasimelteon (T007740). Tasimelteon is a novel drug, used in the treatment of non-24 hour sleep-wake disorder. It helps to correct the circadian rhythm disorder often seen in patients who are visually impaired.

General procedure for the synthesis of 4-vinyl-2,3-dihydrobenzofuran from the compound (CAS: 230642-83-8): dissolve toluene sulfonate of part C (100 g, 314 mmol) in THF (1200 mL) in a 2000 mL three-necked round-bottomed flask equipped with a mechanical stirrer, a digital thermometer, and a homogeneous-pressure charging funnel. Room temperature was maintained. The reaction mixture was cooled to 0 °C via an ice water bath. A THF solution of t-BuOK (1 M, 345.5 mL) was slowly added dropwise at 0 °C for 110 min. The reaction mixture was gradually warmed to ambient temperature and stirring was continued for 2 hours. Upon completion of the reaction, water (350 mL) and EtOAc (600 mL) were added to separate the organic and aqueous layers. The aqueous layer was further extracted with EtOAc (2 x 150 mL). All EtOAc layers were combined, washed with brine (2 × 150 mL), dried over MgSO4 and filtered. The solvent was removed by distillation under reduced pressure to give 46 g of the target product 4-vinyl-2,3-dihydrobenzofuran in 100% yield.

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[2] Journal of Chemical Research, 2016, vol. 40, # 11, p. 667 - 669
[3] Patent: CN106542973, 2017, A. Location in patent: Paragraph 0098-0101