The Chemistry of Derivatives of 2-Benzaltetralone. III. Reaction of 2-Bromo-4,4-dimethyltetralones with Amines. Endocyclic Eliminations

Dehydrobromination of 2-bromo-2-benzyl-4,4-dimethyl-1-tetralone (I) and 2-bromo-2-(α-bromobenzyl)-4,4-dimethyl-1-tetralone (II) can be effected by amines at room temperature, the products being mainly the endocyclic α,β-unsaturated ketones III and VII, respectively. 2-(α-Bromobenzyl)-4,4-dimethyl-1-keto-1,4-dihydronaphthalene (VI) obtained by allylic bromination of III or by loss of hydrogen bromide from II reacts instantaneously with piperidine or morpholine yielding VII. These results are discussed in connection with the new mechanism of dehydrobromination of 2-halo-1-tetralones by amines, previously postulated².