Sodium Hydroxide → tert-butyl 4-(4-carboxyphenyl)-3-[4-(3-methoxypropyl)-3-oxo-3,4-dihydro-2H-benzo[1,4]oxazin-6-ylmethoxy]piperidine-1-carboxylate

Participants

Reaction Conditions

Reaction Steps

A solution of 1,200 g of tert-butyl 4-(4-methoxycarbonylphenyl)-3-[4-(3-methoxypropyl)-3-oxo-3,4-dihydro-2H-benzo[1,4]oxazin-6-ylmethoxy]piperidine-1-carboxylate in 20 ml of dioxane is admixed with 10 ml of 2N NaOH. The reaction mixture is heated to 80° C. over 1 hour and subsequently cooled to room temperature. The phases are separated and the aqueous phase is adjusted to pH 2 with 2N HCl (9.5 ml) and extracted with tert-butyl methyl ether (2×40 ml). The organic phases are combined, washed with 50 ml of water, dried over sodium sulphate, filtered and concentrated by evaporation. The residue is recrystallized from 1:1 ethyl acetate/heptane (20 ml). The title compound is obtained as a colourless solid. Rt=4.48.

Provenance & Evidence