Bromination of 4-Bromoindanone and 5-Bromoindanone, Facile Synthetic Access to 3,5,10-tribromo-7H-benzo[c] fluoren-7-one

Abstract

Bromination reactions of 4-bromoindanone and 5-bromoindanone were presented and optimum reaction conditions were introduced. 2,2,4-Tribromoindanone was synthesized by treatment of 4-bromoindanone with molecular bromine at room temperature in a high yield. Bromination of 4-bromoindanone with NBS, SiO2 and LiClO4 in PEG yielded the corresponding 2,4-dibromoindanone which was reduced to 1-hydroxy-2,4-dibromoindane. Acetylation of hydroxydibromoindane in pyridine gave the 1-acetoxy-2,4-dibromoindane in excellent yield. The radical bromination of 5-bromoindanone with NBS at 77 degrees C in CCl4 yielded the corresponding 3,5-dibromoindene-1-one which was converted to 3,5,10-tribromo-7H-benzo[c] fluoren-7-one by thermolysis.