Hydrochloric Acid → Benzyl 4-(4-methoxycarbonylphenyl)-3-[4-(3-methoxypropyl)-3,4-dihydro-2H-benzo[1,4]oxazin-6-ylmethoxy]piperidine-1-carboxylate

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Reaction Conditions

Reaction Steps

A solution of 3.92 g of benzyl 4-(4-methoxycarbonylphenyl)-3-[4-(3-methoxypropyl)-3-oxo-3,4-dihydro-2H-benzo[1,4]oxazin-6-ylmethoxy]piperidine-1-carboxylate (Example 255d) in 50 ml of chloroform is admixed under argon with 4.27 g of tetrabutylammonium borohydride. The reaction solution is stirred at 60° C. over 19 hours and subsequently cooled to room temperature. 10 ml of 2N HCl and 50 ml of water are subsequently added dropwise. The suspension is stirred at room temperature over 10 minutes. The reaction mixture is poured onto 150 ml of aqueous sodium hydrogencarbonate solution and extracted with 800 ml of tert-butyl methyl ether. The organic phase is washed with 100 ml of water and 50 ml of brine, dried over sodium sulphate, filtered and concentrated by evaporation. The title compound is obtained as a colourless oil from the residue by means of flash chromatography (SiO2 60F). Rf=0.19 (2:1 EtOAc-heptane); Rt=5.34.

Provenance & Evidence