Dimethyl Sulfoxide → Benzothiazole

Participants

Reaction Conditions

Reaction Steps

A mixture of 9,9-diethyl-7-bromo-fluorene-2-carboxaldehyde (49.35 g., 0.15 mol.), 2-aminothiophenol (20 ml. 0.187 mol., 1.25 eq.), and DMSO (110 nl) was heated in an oil bath to a bath temperature of 195° C., held there for 45 minutes, and then poured into water. The separated solids were collected, reslurried in 1:4 acetic acid-water (1000 ml.) filtered, and washed with water and dilute sodium bicarbonate solution. These solids, 80.05 g., were then reslurried in hot ethanol, (600 ml), cooled and filtered to get the product benzothiazole, 45.69 g., m.p. 133.6-135° C. An additional 6.6 g., m.p. 134.6-135.5° C., was obtained by chromatography of the ethanol filtrate. Total recovery was 52.29 g. (80.3% yield). Mass Spec: m/z 433, 435, (M+). Anal. Calcd for C24H20BrNS: C, 66.37; H, 4.64; Br, 18.40; N, 3.23; S 7.37%. Found: C, 66.46; H, 4.52; Br, 18.54; N, 3.14; S, 7.19%.

Provenance & Evidence