Water → tert-Butyl 6-bromo-4-oxo-3,4-dihydro-1'H-spiro[1,3-benzoxazine-2,4'-piperidine]-1'-carboxylate

Participants

Reaction Steps

A mixture of 5-bromo salicylamide (2.5 g, 11.6 mmol), N—BOC-4-piperidone (2.30 g, 11.6 mmol) and pyrrolidine (0.96 ml, 11.6 mmol) in toluene (40 ml) was heated to reflux under N2 atmosphere. After 3 h, the mixture was cooled down to RT, poured into water and extracted with AcOEt. The organic phase was washed with a 2 M solution of NaOH (150 ml) and then with 2 M HCl (150 ml), dried over Na2SO4, filtered and the solvent was evaporated under vacuum. The crude mixture was purified by column chromatography using DCM/MeOH 90/10 as eluent, to give 1.82 g of 6-bromo-3,4-dihydro-4-oxo-spiro[2H-(1,3)-benzoxazine-2,4′-piperidin]-1′-carboxylic acid tert-butyl ester as a white solid (40%). Reaction with methyl acrylate according to the procedure for preparation of Intermediate 1, Step B, gave (E)-3-{1′-tert-butoxycarbonyl-3,4-dihydro-4-oxo-spiro[2H-(1,3)-benzoxazine-2,4′-piperidin]-6-yl}-acrylic acid methyl ester (1.3 g, 71%) as a yellow solid.

Provenance & Evidence