Biscyclophanes. Part 1: synthesis of a common-nuclear bis[1.1.1 ]orthocyclophane. First member of a new family of cyclophanes

Abstract

Synthesis of new orthocyclophane hosts has been investigated by the acid-catalysed intramolecular Friedel–Crafts cycloalkylation of terminal benzylbenzylic alcohols that bear repeating benzyl chains. Treatment of 2-(2-benzylbenzyl)benzyl alcohol 6 with concentrated sulfuric acid in acetic acid medium gave rise to a cyclisation product, [1.1.1]orthocyclophane 2. Similar cyclisation behaviour was observed under the same reaction conditions by the use of diterminal benzylbenzylic diols, which provided a common-nuclear bisorthocyclophane. Treatment of a solution of either the α,ω-benzylic diols 1,3-bis-{2-[2-(hydroxymethyl)benzyl]benzyl}benzene 16 in acetic acid or the 1,4-isomer 20 in acetic acid–dimethyl sulfoxide with concentrated sulfuric acid provided heptacyclo-[19.15.0.0^3,19.0^5,10.0^12,17.0^23,28.0^30,35]hexatriaconta-1 (21 ),2,5(10),6,8,12(17),13,15,19,23 (28), 24,26, 30(35),31,33- pentadecaene 3 which is the first member of a family of novel biscyclophanes.