Methanesulfonic Acid → HCID 23128313, compound

Participants

Reaction Steps

A mixture of 160 ml of methanesulfonic acid and 45 g of P2O5 was heated with stirring at an oil bath for about ½ hr in order to obtain a homogeneous mixture. The mixture was cooled to RT and a solution of 46 g of N-[2-(3-methoxyphenyl)-ethyl]oxalamic acid ethylester, 5b, in 50 ml of CH2Cl2 was added and the temperature was raised again to 80° C., while distilling off the CH2Cl2. The mixture was kept for 16 hr at 80° C. in order to complete the cyclization reaction. Then the reaction mixture was cooled and poured into ice-water and was made alkaline by careful addition of solid K2CO3. The product was extracted into ethyl acetate. The organic layer was washed with water, dried, concentrated and the residue was chromatographed, using a gradient of heptane/ethyl acetate as eluent, to provide 35 g of 6-methoxy-3,4-dihydroisoquinoline-1-carboxylic acid ethyl ester 5c. MS-ESI: [M+1] 234.14. NMR (CDCl3) δ 1.40 (t, 3, OC2H5), 2.72 (m, 2, CH2), 3.85 (s and m, 5, CH2 and OCH3) 4.40 (q, 2, OC2H5), 6.70, 6.80 and 7.70 (3×m, 3, Ar—H).

Provenance & Evidence