MOBILE KETO ALLYL SYSTEMS .5. SYNTHESIS OF 2-(ALPHA-BROMO-SUBSTITUTED BENZYL)-4,4-DIMETHYL-1,4-DIHYDRO-1-KETONAPHTHALENES AND REACTIONS WITH AMINES

Several 2-(±-bromo-X-benzyl)-4,4-dimethyl-1,4-dihydro-1-ketonaphthalenes [X = H(1), p-NO2(2), m-NO2(3), o-NO2(4), and p-Cl (5)] have been prepared by the reaction of N-bromosuccinimide with 2-X-benzal-4,4- dimethyl-1-tetralones. Reaction of 2-(p-dimethylaminobenzal)-4,4-dimethyl-1-tetralone with N-bromosuccinimide gave 2-(m-bromo-p-dimethylaminobenzal)-4,4-dimethyl-1-tetralone (6). 2-(±-Chlorobenzyl)-1,4-dihydro-4,4- dimethyl-1-ketonaphthalene (7) was prepared from 1 by a halogen exchange reaction. The halo ketones 1-5 and 7 reacted with piperidine to give the corresponding 2-(±-piperidino-X-benzyl)-4,4-dimethyl-1,4- dihydronaphthalenes (9-13). The bromo ketone 4 reacted with morpholine to give both 2-(o-nitrobenzal)- morpholino-4,4-dimethyl-1-tetralone (15), in which the allyl system is inverted, and the direct substitution product 14. The bromo ketones 2 and 4 each reacted with t-butylamine to give the corresponding direct substitution products 17 and 18, while 1 and 5 each reacted to give both direct substitution products and the rearranged isomeric t-butylamino ketones. These compounds resulted from parallel courses of reaction of the bromo ketones and were not interconvertable. Possible mechanisms for these amine reactions with ²-keto allyl halides are discussed. © 1968, American Chemical Society. All rights reserved.