7-FLUORO-[1,8]NAPHTHYRIDIN-2-OL synthesis

Yield:846033-37-2 97%

Reaction Conditions:

with hydrogen fluoride-pyridine;NaNO₂ at 0; for 0.5 h;

Steps:

1B

7-Fluoro-1H-[1,8]naphthyridin-2-one; 7-Amino-1H-[1,8]naphthyridin-2-one (290 g, 1.81 mole) was added to a nalgene reactor containing HF pyridine (70%, 1.25 Kg) with cooling via an ice bath. The solution was stirred with a nalgene stir shaft and paddle. Sodium nitrite (150 g, 2.17 more) was added to the reaction carefully in small portions with salt ice bath cooling and vigorous stirring. A vigorous reaction occurred with each addition. The reaction exothermed considerably and evolution of gas was vigorous. After all of the sodium nitrite was added the reaction was vigorously stirred with ice bath cooling under nitrogen. Solids form and the reaction was sampled after 30 min. The reaction was judged complete by ¹H NMR at this time. The reaction was carefully diluted to a volume of approximately 4 L with ice/water. The suspension was suction filtered and the solids washed by resuspending in water (4 L) and suction filtering (3×). The solid material was then resuspended in ethyl acetate (4 L) and suction filtered (2×). The resulting bright yellow filter cake was pooled with another batch (prepared from 190 g of 7-Amino-1H-[1,8]naphthyridin-2-one by a virtually identical procedure and similar stoichiometry of reagents). The pooled material was dried in vacuo to give 7-Fluoro-1H-[1,8]naphthyridin-2-one (478 g, 2.91 mole, 97% yield) as a bright yellow solid. MS: API-ES: M+1: 165.2 (164.04). ¹H NMR (400 MHz, DMSO-d₆) δ 12.34 (s, 1 H), 8.31 (t, J=8.20 Hz, 1 H), 7.97 (d, J=9.67 Hz, 1 H), 7.00 (dd, J=8.20, 2.05 Hz, 1 H), 6.58 (d, J=9.37 Hz, 1 H) CHN Found: C, 58.06; H, 2.89; N, 17.03; F, 11.58; Calc: C, 58.41; H, 3.09; N, 17.03; F, 11.54

References:

US2008/167319,2008,A1 Location in patent:Page/Page column 7