10-Bromo-10-methyl-11-methylene[3.2]paracyclophane (3), available by bromination followed by dehydrobromination of 10,11-dimethyl[3.2]paracyclophane-10-ene (1), reacted with 1,4-diaza-[2.2.2]bicyclooctane (DABCO) by SN 1. Thermolysis of the quaternary ammonium salt 4 produced 10,11-dimethylene[3.2]paracyclophane (5). The Diels-Alder reactivity of 5 exceeds that of 1,4-diphenyl-1,3-butadiene (9) and 2,3-diphenyl-1,3-butadiene (10) and can be used in reactions with suitable dienophiles followed by aromatization to prepare areno-bridged [3.2]paracyclophanes. Similarly, 10,11-diethylidene[3.2]paracyclophane (7) was obtained from 10,11-diethyl[3.2]paracyclophane-10-ene (6) and reacted with dimethyl acetylenedicarboxylate.
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