Triphenylphosphine → 5-[3-Methoxy-4-(2-morpholinoethoxy)phenyl]-3-oxazolo[4,5-b]pyridin-2-yl-pyridin-2-amine

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Reaction Steps

[C2] A solution of di-tert-butyl azodicarboxylate (241 mg) in dichloromethane (1 ml), was added dropwise to a stirred suspension of 4-(6-amino-5-(oxazolo[4,5-b]pyridin-2-yl)pyridin-3-yl)-2-methoxyphenol (130 mg), 2-morpholinoethanol (0.054 ml) and triphenylphosphine polymer bound (350 mg, 1.05 mmol) dissolved in dichloromethane (3 ml). The resulting suspension was stirred at room temperature for 2 hours. The mixture was filtered, washed with dichloromethane (1 ml) and methanol (1 ml). The solvent was evaporated. The resulting residue was diluted with 1 ml of dichloromethane and 1 ml of TFA; the mixture was stirred overnight and concentrated. The reaction mixture was purified by preparative HPLC using a Waters X-Bridge reverse-phase column (C-18, 5 microns silica, 19 mm diameter, 100 mm length, flow rate of 40 ml/minute) and decreasingly polar mixtures of water (containing 0.2% ammonium carbonate) and acetonitrile as eluent. The fractions containing the desired compound were evaporated to dryness to afford 5-[3-methoxy-4-(2-morpholinoethoxy)phenyl]-3-oxazolo[4,5-b]pyridin-2-yl-pyridin-2-amine (70 mg) as a solid. The 4-(6-amino-5-oxazolo[4,5-b]pyridin-2-yl-3-pyridyl)-2-methoxy-phenol used as starting material was made as follows:

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