Synthesis and some transformations of polybrominated quinone diazides

The reduction of polybrominated o - and p -nitrophenols with granular tin in concentrated aqueous HCl gave polybrominated aminophenols which were diazotized with sodium nitrite in concentrated sulfuric acid at 0°C to obtain polybrominated o - and p -quinone diazides. Their thermolysis with elimination of nitrogen generated ketocarbenes which reacted with acetylacetone to form insertion products at the activated methylene group. Ketocarbenes generated from o -quinone diazides reacted with typical dipolarophiles such as acetonitrile, benzonitrile, styrene, and phenylacetylene to afford the corresponding [3 + 2]-cycloaddition products.