tert-Butyl acetate → benzyl 3-(1-(tert-butoxy)-2-methoxy-2-oxoethyl)-2-methyl-4-(p-tolyl)-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate

Participants

Reaction Steps

To a solution of benzyl 3-(1-hydroxy-2-methoxy-2-oxoethyl)-2-methyl-4-(p-tolyl)-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate (intermediate 11) (0.10 g, 0.217 mmol) in CH2Cl2 (3 ml) was added tert-butyl acetate (2.05 ml, 15.2 mmol) followed by HClO4 (0.056 ml, 0.651 mmol). The flask was sealed and stirred at room temperature for 2.5 h. The reaction was quenched with sat'd aq NaHCO3 (gas evolution). The organic phase was dried (Na2SO4), filtered and concentrated. The residue was purified by flash column chromatography (Biotage; 0%-30% EtOAc/hexanes). The product-containing fractions were combined and concentrated to give benzyl 3-(1-(tert-butoxy)-2-methoxy-2-oxoethyl)-2-methyl-4-(p-tolyl)-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate (82.4 mg, 72% yield) as a colorless oil. 1H NMR (400 MHz, CDCl3) δ ppm 7.01-7.78 (m, 9H), 5.13 (s, 2H), 4.97 (s, 1H), 4.29-4.32 (m, 1H), 4.05-4.10 (m, 1H), 3.78-3.81 (m, 2H), 3.71 (s, 3H), 3.06 (bs, 2H), 2.64 (s, 3H), 2.45 (s, 3H) 0.99 (s, 9H). LCMS (M+H) calcd for C31H37N2O5: 517.27. found: 517.4.

Provenance & Evidence