4-Chloropyridine hydrochloride (1.3 g) was added to sodium hydride (0.89 g) in DMSO (20 ml), and the mixture was stirred for 10 min. tert-Butyl 9-hydroxy-3-azaspiro[5.5]undecane-3-carboxylate (2.0 g) in DMSO (20 ml) was then added slowly, and the mixture was stirred overnight (TLC monitoring: conversion about 30-35%). A catalytic amount of sodium iodide was added, and the reaction mixture was stirred for 8 h at 80° C. (TLC monitoring). Methanol and NaHCO3 solution were added to the reaction mixture, and stirring was carried out for 20 min. Extraction with ethyl acetate was then carried out, followed by washing with NaHCO3 solution and cold water. The organic phase was dried (Na2SO4) and concentrated under vacuum. The resulting crude product was purified by column chromatography (silica gel, 70% ethyl acetate/hexane). Yield: 1.0 g (40%)
