Acetic Acid → HCID 21184385, compound

Participants

Reaction Conditions

Reaction Steps

A suspension of 1.00 g (0.003 mol) of 4,9-dihydro-4,9-dioxo-8-methoxy-2-phenyl-naphtho[2,3-d]-thiazole (Example 23) in 67 mL (1.160 mol) of acetic acid and 67 mL (0.570 mol) of hydrobromic acid is heated to reflux for 5 h 30 min. After cooling to 10° C., the reaction medium is filtered through fritted glass. The precipitate consists of 200 mL of chloroform. The organic phase is washed with a 3% ammonia solution (3×40 mL) and dried over calcium chloride. The yellow solid obtained after evaporation at reduced pressure of the solvent is purified on a medium-pressure column (support: silica 6-35 mm, eluant: toluene/dichloromethane, 100/0, 50/50, 0/100), then recrystallized 3 times in a toluene/heptane mixture, 50/50, to produce 0.302 g of 4,9-dihydro-4,9-dioxo-8-hydroxy-2-phenyl-naphtho[2,3-d]thiazole.

Provenance & Evidence