A solution of 0.345 g of tert-butyl 4-{4-[3-(2-methoxybenzyloxy)propoxy]phenyl}-3-(2-oxo-1-(2-trimethylsilanylethoxymethyl)-2,3,4,5-tetrahydro-1H-benzo[b]azepin-9-ylmethoxy)piperidine-1-carboxylate in 4 ml of tetrahydrofuran is admixed with 0.85 ml of a 1M solution of tetrabutylammonium fluoride in tetrahydrofuran. The reaction solution is heated to reflux over 4 hours. A further 0.85 ml of tetrabutylammonium fluoride solution is added and the reaction solution is subsequently heated to reflux over a further 20 hours. The reaction solution is cooled and admixed with 50 ml each of water and tert-butyl methyl ether. The aqueous phase is removed and extracted with 40 ml of tert-butyl methyl ether. The combined organic phases are washed with 40 ml of brine, dried over sodium sulphate, filtered and concentrated to dryness. The title compound is obtained as a yellow oil from the residue by means of flash chromatography (SiO2 60F). Rf=0.25 (3:1 EtOAc-heptane); Rt=4.34.
