Substituted .gamma.-butyrolactones. Part 37: reactions of (arylmethylene)furandiones with nucleophiles. A novel approach to the cyclolignan lactone skeleton

Total Synthesis of (±)-Meridinol, (±)-Epimeridinol, and a Related Cyclolignan

“…3-Hydroxy-4-(3.4-methylenedioxybenzoyl)-2(5H)-furanom [6].-A 2-liter three-necked round-bottom flask equipped with a heavy-duty stirrer, thermometer, and 250 ml pressure-equalized addition funnel, was charged with NaOMe (6 g, 0.111 mol) and dry Et,0 (100 ml). The suspension was cooled to 0-5°, and a mixture of 3,4-methylenedioxyacetophenone (18.2 g, 0.111 mol), diethyl oxalate (16.2 g, 0.111 mol), and dry Et,O(100 ml) was added in small portions with stirring over a period of 30 min while maintaining the temperature at 5-10°.…”

“…Based on this assumption the total synthesis of (±)-meridinol was contemplated to proceed according to Scheme 2. Thus, 3-hydroxy-4-(3,4-methylenedioxybenzoyl)-2(5H)-furanone [6] was easily obtained from the commercially available 3,4methylenedioxyacetophenone by a known procedure (8). Further treatment of 6 with NaBH4 gave (£)-4-(3,4-methylenedioxybenzylidene)-2,3(4H,5f/)-furandione [7] in 66% yield.…”

“…The desired compound 9 finally was prepared by slowly adding a dilute solution of piperonyl chloride to magnesium powder in dry Et20 without any heating. The reaction of 7 with 9 using the same conditions as employed in our previous work (6) was monitored by tic and quenched after disappearance of the starting material. Purification by flash cc of the crude product yielded two compounds which were identified on the basis of their elemental analysis and mass and nmr spectra as 8 and 10.…”