Butantrone synthesis

Yield:-

Reaction Conditions:

with pyridine in water;toluene;

Steps:

13.a (a)

(a) 1,8-Dihydroxy-10-butyrylanthrone To a stirred suspension of 51 g (0.22 mol) of 1,8-dihydroxyanthrone in 1.5 liters of toluene, kept under an inert atmosphere and shielded from light, 23.8 cm³ of pyridine was first added all at once and then 27.4 cm³ of butyryl chloride was added dropwise over 15 minutes. The mixture was then heated to a temperature of 80°-90° C. for 1 hour. Subsequently, the same quantities as before of pyridine and butyryl chloride (i.e., a total of 2.7 molar equivalents for pyridine and of 2.4 molar equivalents for the acid chloride) were added at room temperature. The reaction mixture was then reheated to 80°-90° C. for 1 hour. After being cooled to room temperature, the mixture was poured into 500 cm³ of acidulated water. The organic phase was decanted, washed with water until the washings became neutral and dried over magnesium sulfate. This phase was then fractionated by chromatography on a silica gel column, using toluene as the mobile phase. The eluted phases were concentrated and poured into hexane, thus causing crystallization of 1,8-dihydroxy-10-butyrylanthrone. The solvent was sucked from this product, which was then dried to yield 20 g of yellow crystals having a melting point of 138° C. Analysis: C₁₈ H₁₆ O₄ Calc.: C 72.96, H 5.44, O 21.60; Found: C 72.75, H 5.48, O 21.38.

References:

US4696941,1987,A