tert-Butyl piperazine-1-carboxylate → 8-(4-Tert-butoxycarbonyl-piperazin-1-yl)-6-chloro-2,3-dihydro-benzo[1,4]oxazine-4-carboxylic acid benzyl ester

Participants

Reaction Conditions

Reaction Steps

A three neck flask was charge with tris(dibenzylideneacetone)dipalladium(0) (21.5 mg, 0.024 mmol, 2 mol % Pd), (±)-2,2′-bis(diphenylphosphino)-1,1′-binaphthyl (36.4 mg, 0.059 mmol, 5 mol %) and sodium-tert-butoxide (159 mg, 1.65 mmol) and flushed with nitrogen. A solution of 8-bromo-6-chloro-2,3-dihydro-benzo[1,4]oxazine-4-carboxylic acid benzyl ester (450 mmg, 1.18 mmol) and piperazine-1-carboxylic acid tert-butyl ester (263 mg, 1.41 mmol) in toluene (2 mL) was added. The mixture was heated to 95° C. and was stirred for 12 hours. The mixture was cooled to room temperature, taken up in ethyl acetate, filtered through celite and concentrated. The crude material was purified by flash chromatography on silica gel (eluting with hexane-ethyl acetate; 7:3, v/v) to give 8-(4-tert-butoxycarbonyl-piperazin-1-yl)-6-chloro-2,3-dihydro-benzo[1,4]oxazine-4-carboxylic acid benzyl ester a colorless oil (275 mg, 48%). MS: MH+=488.

Provenance & Evidence