Methyl azepane-4-carboxylate hydrochloride can be used to prepare methyl 1-(2-chloro-5-(3-methoxypropyl)pyridin-3-yl)azepane-4-carboxylate by reacting with 3-bromo-2-chloro-5-(3-methoxypropyl)pyridine. The specific synthesis steps are as follows:
To a stirred solution of 3-bromo-2-chloro-5-(3-methoxypropyl)pyridine (200 mg, 756 μmol, 1 .0 eq) in toluene (2 mL), was added methyl azepane-4-carboxylate HCl (190 mg, 983 μmol, 1.3 eq), and Cs2CO3(739 mg, 2.27 mmol, 3 eq). The resulting reaction mixture was purged with N2 (g) for 10 min. Next, Pd2(dba)3 (35 mg, 38 μmol, 0.05 eq) and 9,9-dimethyl-9H-xanthene-4,5- diyl)bis(diphenylphosphane) (Xantphos) (44 mg, 76 μmol, 0.1 eq) were added respectively and the resulting reaction mixture was again purged with N2 (g) for 5 min. The resulting reaction mixture was heated to 110°C and stirred for 16 hr. The reaction mixture was then cooled to rt and filtered. The filtrate was concentrated under vacuum. The residue was purified by silica gel column chromatography (PE:EtOAc=10: 1 to 5:1) to afford methyl 1 -(2- chloro-5 -(3 -methoxy propyl)pyridin-3-yl)azepane-4-carboxylate (80 mg, 31 % yield) as colorless liquid. LCMS calculated for C17H25CIN2O3: m/z = 340; found: m/z = 341 (M+H).
