MEDIUM-SIZED CYCLOPHANES .30. PREPARATION AND CONFORMATIONAL STUDIES OF 1,4-DISUBSTITUTED 10,15-DIHYDRO-5H-TRIBENZO[A,D,G]CYCLONONENES AND THE CORRESPONDING BIS[1.1.1]ORTHOCYCLOPHANE

The reaction of i-tert-butyl-2,2'-bis(chloromethyl)diphenylmethane (1) with p-dimethoxybenzene (2) performed in acetic acid for 24 h in the presence of zinc chloride as a catalyst led to the desired cyclobenzyl ation reaction to give ethoxy-10,15-dihydro-5H-tribenzo[a,d,g]cyclonon ene (3c) in 22% yield along with, in 10% yield, the bis-benzylation pr oduct (4); the latter adopts a conformationally flexible double saddle structure in comparison with the rigid crown structure of 3c.