Some quaternary 22-disubstituted biphenyls

Abstract

In only a few cases can a reasonably valid comparison be made between the optical stabilities of unbridged biphenyls and those bridged with a 7-membered bridging ring. An attempt was made in this work to prepare bridged and unbridged biphenyl compounds with similar interfering groups and to compare their optical stabilities. Quaternary salts derived from various 2,2'-bisbromomethylbiphenyls were chosen since by condensation of the latter with suitable amines analogous bridged and unbridged biphenyls can be produced, with the further advantage that the resolving groups are not directly attached to the biphenyl nucleus.2-Bromomethyl-1-(o-bromomethylphenyl)naphthalene was synthesised and 2,7-dihydronaphtho(2',1' :3,4)-5,6-benzasepinium-1-spiro-1'''-piperidinium iodide and 2,2,-'bis(N-pyridinium-methyl)-5,6-benzbiphenyl dibromide were obtained. Attempts to prepare more of the dipyridyl salt or to obtain salts with other tertiary bases were not successful.2,2'-Dimethyl-4,4'-dinitrobiphenyl was synthesised. However on side-chain bromination it gave a mixture of mono-and dibromo-compunds of very similar solubilities.2,2,-Bisbromomethylbiphenyl was condensed with N-methylephedrine, pyridine, trimethylamine and dimethylamine.No unstable optical activity was detected in the resulting quaternary salts. The salts were subjected to Hofmann degradation conditions. The bis-ephedrinium hydroxide gave the expected 2,2'-bis(dimethylaminomethyl)biphenyl in appreciable yields only when carbon dioxide was excluded ; the diamine was accompanied by: (-) -N-methylephedrine, 9-dimethylamino-9,lQ-dihydro-phenanthrene and the 2,7-dibydro-l,1-dimethyl-3,4:5,6-dibenz-azepiniua cation. 9-Dimethylamino-9,10-dihydrophenanthrene was also isolated from the products of Hofmann degradation of 2,2'-bis (trimethylammoniomethyl) biphenyl and of 2,7-dihydro-1,1-dimethyl-5,4:5,6-dibenzazepinium hydroxides. This seems to indicate Incursion of a Stevens type of rearrangement into the normal Hofmann degradation of these salts 2,2'-Bibromomethyl-4- and -6-nitrobiphenyls have been synthesised and condensed with (-)-ephedrine, dimethylamine and trimethylamine. The 2,7-dihydro~l-methyl-1-(b -hydroxy- a-methyl- B-phenylethyl)-4'-nltro-5,4:5,6-dibenzazepinium salt was separated into at least two diastereoisomers both of which showed unstable optical activity at room temperature. (-)2, 7-Dihydro-1, 1-dimethyl 3-5,4: 5,6-dibenzazepiniuza picrate was obtained and its racemisation in acetone was studied. 2,2'-Bis-(trimethylamrnoniomethyl) -6-nltrobiphenyl (+) Camphorsulphonate was prepared.