Phosphoric Acid → 2,2-Dimethyl-5-(3-methyl-3-buten-1-ynyl)-4H-(1,3)benzodioxin-4-one

Participants

Reaction Conditions

Reaction Steps

0.64 g (0.92 mmol) of bistriphenylphosphinepalladium dichloride, 4.4 ml (46 mmol) of 3-methyl-3-buten-1-yne and 24 ml of triethylamine are added under nitrogen to a solution of 15.0 g (46 mmol) of 2,2-dimethyl-5-trifluoromethylsulfonyloxy-4H-(1,3)benzodioxin-4-one in 150 ml of dimethylformamide. The mixture is heated at 115° C. for 0.5 h, a further 6.6 ml of 3-methyl-3-buten-1-yne are then added at this temperature in the course of 1 h and the reaction solution is subsequently stirred for 15 min. After cooling, it is poured into 500 ml of water containing phosphoric acid (pH 3) at 0° C. and extracted with methyl tert-butyl ether, and the combined organic phases are carefully washed with water and saturated sodium chloride solution, dried over sodium sulfate and concentrated. 14 g of a dark oil remain, which is chromatographed on silica gel using n-hexane/ethyl acetate. 7.0 g of colorless crystals are obtained, m.p. 60 ° C. (cf. Table 1, No. 1.009).

Provenance & Evidence