Oxalic Acid → HCID 21318712, compound

Participants

Reaction Steps

Acetylene, purified by passing it first through a column of alumina, then through concentrated sulfuric acid, was bubbled rapidly through freshly distilled tetrahydrofuran (100 ml) under nitrogen for 30 minutes. Ethylmagnesium bromide (3 ml, 3.15 M in ether, 12.6 mmole) was added in portions. When the frothing subsides, portionwise addition of the ethylmagnesium bromide solution was continued until the total solution had been added. The passage of acetylene was stopped and 7,10-dihydro-6,11-dihydroxy-5,9,12(8H)-naphthacenedione (VII) (250 mg, 0.12 mmole) in dry tetrahydrofuran (240 ml) was added dropwise. An immediate blue color was noted. After addition was completed, the mixture was stirred at room temperature under dry nitrogen overnight. To the dark blue solution was added 5% aqueous oxalic acid solution until the blue color disappeared and the brown reaction mixture extracted with chloroform. The chloroform extracts were washed well with water, dried over anhydrous sodium sulfate and the solvent removed to give a dark residue. The residue was chromatographed on Florisil (100-200 mesh) elution with methylene chloride, then with 2% methanol/methylene chloride yielded 9-ethynyl-7,10-dihydro-6,9,11-trihydroxy-5,12(8H)-naphthacenedione (VIII) (200 mg, 91%) as a red orange solid. m.p. 230° C. with decomposition; IR 6.15, 6.30μ; MS 334 (M+) 317 (M-OH); NMR (CDCl3) 13.40 (s 2H OH's), 8.3 (m 1H aryl), 7.7 (m 1H aryl), 3.1 (m 4H benzylic), 2.5 (s 1H ethynyl), 2.16 (m 2H allylic); UV (CHCl3) 289, 460, 485, 518 nm; PFT (CDCl3) δ13.46 (s 2H OH), 8.34 (m 2H aryl), 7.81 (m 2H aryl), 2.06 (t 2H benzylic), 2.50 (s 1H ethynyl), 2.15 (t 2H allylic).

Provenance & Evidence