Dibromination of [2.2]paracyclophane (I) led to predominantly pseudo-ortho2 (II) and pseudo-para2 (III) disubstituted compounds, and to lesser amounts of pseudo-meta (IV) and para (V) isomers. Oxidation of these dibromides gave terephthalic acids whose esters were identified by vpc, and whose structures allowed homoannular and transannular bromination to be differentiated. Tetrabromination of I gave compound VI with two p-bromines in each ring with a set of pseudo-ortho and a set of pseudo-para relationships between transannular bromines. This compound by lithiation and methylation of the organometallic gave the known tetramethyl[2.2]paracyclophane, VIII. Dibromination of dibromide II also gave VI. Compound VII was also isolated from the tetrabromination of I and the dibromination of III; it contains two o-bromines in each ring with a set of pseudo-meta and a set of pseudo-para relationships between transannular bromines. Dehalogenation of VII with n-butyllithium in the presence of furan gave the bis(furan)benzyne adduct IX, which was converted to the known [2.2]paracyclonaph-thane. Dibromide III was converted to dilithium derivative X. Methylation of X gave pseudo-p-dimethyl[2.2]-paracyclophane2 (XI). Oxidation of X produced the pseudo-p-dihydroxy derivative, XII, and iodination, the pseudo-p-diiodo derivative, XIII. Dibromide II was also lithiated, and the dilithio derivative converted to pseudo-o-dihydroxy[2.2]paracyclophane2 (XVI). Attempts to oxidize diphenols XII and XVI to the corresponding bis quinones failed. Cuprous cyanide cyanation of pseudo-o- or pseudo-p-dibromo compounds (II or III) at 225° gave, besides a mixture of II and III, four compounds: pseudo-o-bromocyano[2.2]paracyclophane (XVIII), pseudo-p-bromocyano[2.2]paracyclophane (XIX), pseudo-o-dicyano[2.2]paracyclophane(XX), and pseudo-p-dicyano[2.2]-paracyclophane (XXI). Thermal isomerization by ring rotation accompanied substitution. The yield pattern showed no difference in activation or deactivation effects between the bromo and cyano groups toward the cyanation reaction. Chlorination of I was less discrete than bromination, and only pseudo-p-dichloro[2.2]paracyclo-phane (XXII) was isolated from a multitude of products. Dinitration of I gave four dinitro derivatives whose yield pattern revealed little evidence of a dominant transannular directive effect of a nitro group in one ring on the position of entry of a second into the transannular ring. The presence of the pseudo-gem isomer (XXIII), along with the pseudo-m- (XXIV), pseudo-o- (XXV), and pseudo-p- (XXVI) dinitro[2.2]paracyclophanes, indicates the availability of the special mechanism for proton transfer in the pseudo-gem ü complex for introduction of the second nitro group into the system. © 1969, American Chemical Society. All rights reserved.
