p-Toluenesulfonic acid monohydrate → (2S)-2-[(benzylamino)methyl]-2,3,8,9-tetrahydro-7H-[1,4]dioxino[2,3-e]indol-8-one 4-methylbenzenesulfonate

Participants

Reaction Conditions

Reaction Steps

A 50 mL two necked flask equipped with a magnetic stir bar, gas inlet adapter and gas outlet adapter is charged with {(3S)-3-[(benzylamino)methyl]-6-nitro-2,3-dihydro-1,4-benzodioxin-5-yl}acetic acid [from above (1.36 g, 3.80 mmol)], methanol (20 mL), and p-toluenesulfonic acid monohydrate (1.80 g, 9.5 mmol) and platinum (5% on carbon, 62% w/w water, 0.27 g). The flask head space is flushed with hydrogen gas (100 mL), the gas outlet adapter is closed and the slurry is stirred under a hydrogen atmosphere for 18 h under hydrogen, at which point the reaction is complete by LCMS. The catalyst is removed by vacuum filtration, and the resulting solution is heated to 50° C. (external) in an oil bath for 48 h. The solids are collected by vacuum filtration, the filter cake is washed with cold MeOH (10 mL) and dried under nitrogen giving (2S)-2-[(benzylamino)methyl]-2,3,8,9-tetrahydro-7H-[1,4]dioxino[2,3-e]indol-8-one 4-methylbenzenesulfonate (1.12 g, 61%) as an off-white powder.

Provenance & Evidence