tert-butyl 2-chloro-7,8-dihydro-l,6-naphthyridine- 6(5H)-carboxylate.

Synthesis of tert-butyl 2-chloro-7,8-dihydro-l,6-naphthyridine-6(5H)-carboxylate. To a slurry of 2-chloro-5,6,7,8-tetrahydro-l,6-naphthyridine hydrochloride (106.1 g, 517 mmol, commercially available from D-L Chiral Chemicals, ST-0143) and N,N-diisopropylethylamine (80 g, 108 mL, 621 mmol, 1.2 eq) in DCM (1 L) was added a solution of di-tert-butyl dicarbonate (119 g, 543 mmol, 1.05 eq) in

DCM (100 mL) via an addition funnel within 1 hr. The reaction mixture became a clean solution and the solution thus obtained was stirred at room temperature for an additional hour and monitored using LCMS. Upon completion, the reaction mixture was concentrated. The residue was dissolved in EtOAc (1 L) and washed with water (3 x 300 mL), washed with brine (300 mL) and dried over MgSOzt. The solvent was evaporated under vacuum to give the title compound as an off- white solid (139 g, yield: 100%).

 ^lH NMR (400MHz ,CDC1₃) δ ppm 

1.49 (9H, s),  9 Tert butyl methyls protons

2.97 (2H, t, J= 5.9 Hz), BOC N CH2 CH2 AR

3.73 (2H, t, J= 6.0 Hz), BOC N-CH2 -AR

4.57 (2H, s),Boc-N-CH2-CH2.Ar

7.17 (1H, d, J= 8.0 Hz), 

7.38 (1H, d, J= 8.0 Hz) ppm;