“…The diastereomeric dimers were isolated by high-performance LC (eluant 40% ether in hexane). For isomer 1: yield 0.080 g; white solid; mp 84-86 °C; IR (CC14) 3040,1675 cm1 2; NMR (60 MHz, CDC13) 6.97 (dt, 2 H, Jd = 10 Hz, Jt = 3 Hz, CH2CH=CHCO), 6.0 (dt, 2 H, Jd = 10 Hz, =/, = 1.5 Hz, CH2CH=CHCO), 3.27 (dd, 2 H, J = 11 Hz, 7 Hz, COCHCH2), 2.45 (m, 4 H, =CHCH2CH2CH), 1.92 (m, 4 H, =CH2CH2CH2CH). For isomer 2: yield 0.140 g; white solid; mp 90-100 °C; IR (CC14) 3040, 1675 cm"1; NMR (60 MHz, CDClg) 6.93 (dt, 2 H, Jd = 10 Hz, Jt = 4 Hz, CH2CH=CHCO), 6.02 (dt, 2 H, Jd = 10 Hz, Jt = 3 Hz, CH2CHCHCO), 2.88 (t, 2 H, J = 7 Hz, COCHCH2), 1,4-Bis( endo-3-bicyclo[2.2. l]hept-2-enyl)butane-1,4-dione (9).…”