tert-Butyl 3-(1,8-naphthyridin-2-yl)propylcarbamate → 2-(3-(Boc-amino)-propyl)-5,6,7,8-tetrahydro-1,8-naphthyridine

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Reaction Steps

A solution of naphthyridine 1-4 (2.72 g) in methanol (20 mL) was hydrogenated in the presence of 5% rhodium on carbon (2.1 g; containing 63% of water) under 40 psi of hydrogen at 5° C. for 10 hours. The catalyst was filtered through Solka Flok and washed with methanol (25 mL twice). The filtrate and washings were combined, concentrated in vacuo, and dissolved in methanol (6.8 mL). To the solution was added water (6.8 mL) slowly at ambient temperature. The resulting solid was collected by filtration, washed with a mixture of water and methanol (2:1; 5 mL), and dried under vacuum to give the desired crystalline tetrahydronaphthyridine 1-5 (1.9 g). The mother liquor yielded an additional 5% of 1-5; m.p. 95.2-96.3° C.

Provenance & Evidence