Cycloadditions to Alkenyl[2.2]paracyclophanes

Abstract Cycloadditions between the 4‐alkenyl[2.2]paracyclophanes 7 , 16 – 21 and the dienophiles 10a – h have been studied. Whereas 10a , b , d , and g prefer Diels–Alder addition involving the olefinic double bond and one double bond of a cyclophane benzene ring, 10c , e , f , and h undergo other cycloadditions such as ene reaction ( 10c ), [2+2] cycloaddition to the olefinic double bond ( 10e ) and heterodiene addition to the vinyl substituent ( 10f , h ). Several of the isolated cycloadducts (e.g. 24 – 26 , 52 ) are valuable substrates for the preparation of annelated cyclophanes. The mechanisms of several of these cycloadditions are discussed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)