Carbon Dioxide → 3,8-Dimethoxy-2-naphthoic acid

Participants

Reaction Steps

n-Butyllithium (2.5M in hexanes; 220 ml) was added dropwise at 700° C. under nitrogen to a stirred solution of 1,6-dimethoxynaphthalene (95 g) in tetrahydrofuran (1000 ml). N, N, N', N'-Tetra-methylethylenediamine (150 ml) was added and the mixture was stirred at ambient temperature for 20 hours, then cooled to -20° C. and poured onto crushed solid carbon dioxide (500 g). When effervescence had ceased, the mixture was diluted with water (1000 ml), basified by the addition of sodium carbonate (100 g), washed with ether (2×100 ml) and acidified by the addition of concentrated hydrochloric acid. The product was extracted into ethyl acetate and the extracts were washed with brine, dried over magnesium sulphate, and the solvents removed in vacuo. The residue crystallised from ethyl acetate to give a solid which was collected by filtration, dried in vacuo, and ground to give 3,8-dimethoxy-2-naphthoic acid as a cream powder (45.6 g), m.p. 151°-153° C. Concentration of the liquor yielded a second crop of 3,8-dimethoxy-2-naphthoic acid (5.4 g).

Provenance & Evidence