Diethylazodicarboxylate (3.73 g) was added dropwise to a mixture of tert-butyl (3R)-3-hydroxypiperidine-1-carboxylate (4.29 g), 4-chloro-6-methoxyquinazolin-7-ol (3.00 g) and triphenylphosphine (5.61 g) in methylene chloride (75 ml). The solution was then heated to 0° C. and stirred for 3 hours. After cooling the mixture was filtered and then purified by flash column chromatography eluting with isohexane/acetone/triethylamine (80/20/1) to give tert-butyl (3S)-3-[(4-chloro-6-methoxyquinazolin-7-yl)oxy]piperidine-1-carboxylate as a colourless oil (3.29 g) which was used directly; Mass Spectrum: (M+H)+ 394.
