Hydrochloric Acid → 1-(2-(5-Amino-4-oxopentanoyloxy)ethyl)-2-ethyl-3,4-dihydroxypyridinium chloride hydrochloride

Participants

Reaction Steps

A stirred solution of 2-(3-(benzyloxy)-2-ethyl-4-oxopyridin-1(4H)-yl)ethyl 5-(benzyloxycarbonylamino)-4-oxopentanoate (7) (247 mg, 0.475 mmol) in 6:1 v/v ethanol:water (3.5 mL) was acidified to pH=1 by addition of hydrochloric acid (37% aq.). Palladium on activated charcoal (11 mg, 10% w/w) was added, the reaction vessel was evacuated then filled with hydrogen and the reaction was stirred under hydrogen (at atmospheric pressure) for 2 h. The resulting suspension was filtered through Celite®, eluting with ethanol and the filtrate was then concentrated in vacuo to give the product as a mixture of mono- and di-salts. Three cycles of dissolution in water, addition of hydrochloric acid (37% aq.) then concentration in vacuo gave the title compound 8 (169 mg, 96%) as a brown oil, δH (300 MHz; D2O) 7.82 (1H, d, J 8.0 Hz, Ar 6-H), 6.92 (1H, d, J 8.0 Hz, Ar 5-H), 4.27 (2H, t, J 6.0 Hz, OCH2CH2), 3.91 (2H, s, H3N+CH2), 3.74 (2H, t, J 6.0 Hz, OCH2CH2), 2.80 (2H, q, J 7.0 Hz, CH3CH2), 2.66 (2H, t, J 6.0 Hz, C(O)CH2), 2.45 (2 H, t, J 6.0 Hz, C(O)CH2) and 0.98 ppm (3H, t, J 7.0 Hz, CH3); δC (75 MHz; D2O) 204.3, 176.9, 158.6, 147.7, 142.5, 139.5, 111.0, 60.6, 57.8, 47.3, 34.6, 27.6, 20.1 and 11.3 ppm; m/z (ES+) 297.1445 (100%, [M-H-2Cl]+), C14H21N2O5 requires M, 297.1445.

Provenance & Evidence