MEDIUM-SIZED CYCLOPHANES .31. SYNTHESIS AND ELECTROPHILIC SUBSTITUTION OF 8-SUBSTITUTED [2]METACYCLO[2] (1,3)PYRENOPHANES

syn- and anti-2,11-Dithia[3]metacyclo[3](1,3)pyrenophanes 15 have been obtained by coupling the corresponding 1,3-bis(bromomethyl)pyrene 11 and 1,3-bis(mercaptomethyl)benzenes 14 in ethanol under high-dilution conditions. Oxidation of the obtained thiametacyclophanes 15 with m-ch loro-perbenzoic acid afforded the corresponding syn- and anti-disulfon es 18. Pyrolysis of the syn- and anti-disulfones 18 afforded exclusive ly the corresponding anti-[2]metacyclo[2](1,3)pyrenophane 19 in 40-70% yield along with the ring-cleavage product, 7-tert-butyl-1,3-dimethylp yrene 8.The nitration of 5,15-di-tert-butyl-8-methyl- 19b and rt-butyl -8-methoxy-[2]metacyclo[2](1,3)pyrenophane 19d with 1 mol equiv. of co pper(II) nitrate in acetic anhydride solution exclusively occurred on the more reactive pyrene ring to afford 14-nitro derivatives 21a and 2 1b in 83 and 86% yield, respectively. On the other hand, the brominati on of substrates 19 with bromide in methylene dichloride solution affo rded 1 3-bromo derivatives 23 along with the transannular cyclization products 24 and 25. These different orientations for the electrophilic substitution are also discussed.