tert-Butyl methyl ether → 1-{4-[(S)-4-(2,3-Dihydro-[1,4]dioxino[2,3-b]pyridin-3-yl)-benzyl]-piperazin-1-yl}-2-hydroxy-ethanone

Participants

Reaction Steps

To a solution of Intermediate S (5.80 g, 17.7 mmol) in DCM (200 mL) at 0° C. is added acetic acid chlorocarbonylmethyl ester (2.16 mL, 19.5 mmol) followed by DIPEA (7.50 mL, 35.4 mmol) and the mixture stirred at rt for 1 h. The reaction was concentrated and the residue dissolved in 4:1 MeOH/water (100 mL) then treated with LiOH monohydrate (2.23 g, 53.1 mmol). After 72 h, the reaction is poured into ice water and the resulting solid isolated by filtration. The solid is suspended in refluxing tert-butylmethyl ether (400 mL) for 20 min and the remaining undissolved material separated out by filtration. The cooled filtrate produces a solid that is then isolated by filtration in several crops. The undissolved material from the first filtration is dissolved in refluxing 1,4-dioxane and cooled to give an additional crop of solid. The crops are combined to give the title product 253. (LC/MS method 16: ES+ m/z 370.3 [M+H]+, Rt=0.35 min)

Provenance & Evidence