INTERACTIONS AND CHEMISTRY OF 1,8-BIS(PHENYLETHYNYL)-NAPHTHALENE AND 1,8-BIS(1-ALKYNYL)NAPHTHALENES

The perl-diacetylenes, 1,8-bis(phenylethynyl)naphthalene (I) and 1,8-bis(1-alkynyl)naphthalenes (Ila-c), have been prepared from 1,8-diiodonaphthalene (III) and appropriate cuprous acetylides in pyridine. The ultraviolet absorption maxima of I are at slightly longer wavelengths than those of l,5-bis(phenylethynyl)naphthalene (IV). The moderate nmr shielding and the absorption in I indicate that its phenyl groups may be moved apart and there may be some transannular acetylenic interaction upon its electronic excitation. Thermolysis or photolysis of I yields 7-phenylbenzo[k]fluoranthene (VI); reaction of I with iron pentacarbonyl gives acecycloneiron tricarbonyl (XIV). Bromination of I occurs by transannular 1,4 addition yielding 1,2-bis(α-bromobenzylidene)acenaphthene (XVI). XVI reacts with magnesium or n-butyllithium to give I, VI, and 7-bromo-12-phenylbenzo[k]fluoranthene (XXIII). Photolysis or thermolysis of XVI results in XXIII. Absorption in IIa occurs at slightly longer wavelengths than in 1,5-bis(l-propynyl)naphthalene (XXVII); transannular electronic interaction of the acetylene groups in IIa upon excitation is not large. Addition of 2 equiv each of bromine, hydrogen bromide, and hydrogen iodide to IIa occurs without net transannular structural change to yield 1,8-bis(1,2-dibromo-1-propenyl)naphthalene (XXVIII), 1,8-bis(1 -bromo-1 -propenyl)naphthalene (XXIXa), and 1,8-bis(l-iodo-l-propenyl)naphthalene (XXIXb), respectively. perl-Diacetylene I adds 2 equiv of hydrogen bromide to give the adduct C26H18Br2. © 1969, American Chemical Society. All rights reserved.