SYNTHESIS OF 1-BROMO-6H-BENZO[CD]PYREN-6-ONE

Abstract

1-Bromonaphthanthrone (1-bromo-6H-benzo[cd]pyren-6-one), a useful starting material for the synthesis of undecacyclic aromatic hydrocarbons, was synthesized by means of glycerol condensation of 1-bromopyrene. The structure of the synthetic product was confirmed by NMR measurements and the ¹ H and ¹³ C chemical shifts were completely assigned. Although the synthetic method provided three possible isomers, 1-, 3-, and 5-bromonaphthanthrone, only 1-bromonaphthanthorone was obtained as a final product. An explanation for the regioselectivity was given in terms of the charge distribution obtained by molecular orbital calculations.

Keywords:

• 6H-benzo[cd]pyren-6-one
• bromination
• glycerol condensation
• NMR
• molecular orbital calculations

The authors are grateful to Profs. Emeritus I. Oonishi and J. Aoki and Dr. Y. Fujimaki for helpful discussions.