7,8-dimethoxy-2,3,4,5-tetrahydro-1H-benzo[c]azepine hydrochloride

Synthesis

The general procedure for the synthesis of 7,8-dimethoxy-2,3,4,5-tetrahydro-1H-benzo[C]azepin-1-one from 7,8-dimethoxy-2,3,4,5-tetrahydro-1H-benzo[c]azepine hydrochloride is as follows: 7,8-dimethoxy-2,3,4,5-tetrahydro-1H-benzo[C]azepin-1-one (1 equiv.) was suspended in dry tetrahydrofuran (THF) and the suspension was cooled in an ice bath under nitrogen protection. Subsequently, a solution of borane in THF (3 eq.) was slowly added dropwise. After the dropwise addition was completed, the reaction mixture was heated to 70 °C and refluxed overnight. Upon completion of the reaction, the mixture was again cooled in an ice bath, and a large excess of methanol and 5N hydrochloric acid solution (in equal amounts) were added sequentially. The resulting solution was heated to 90 °C and maintained for 2 hours. Subsequently, the solvent was removed by evaporation. The final product was obtained as purified 7,8-dimethoxy-2,3,4,5-tetrahydro-1H-benzo[c]azepine hydrochloride by recrystallization from a solvent mixture of dichloromethane (CH2Cl2) and methanol (MeOH).

References

[1] Bioorganic and Medicinal Chemistry, 2008, vol. 16, # 5, p. 2499 - 2512
[2] Patent: US2005/165004, 2005, A1. Location in patent: Page/Page column 9-10