Reaction Steps
A mixture of 3,4′-di-(benzyloxycarbonylbutylcarbonyloxy)flavone (435 mg, 0.629 mmol) and Pd(OH)2 (50 mg) in EtOAc (5 mL) was treated with hydrogen for 2 h resulting in a grey precipitate. THF was added to dissolve the precipitate and the mixture was filtered (Celite). The pad washed with THF, and the filtrate concentrated. The solid residue was recrystallised from THF/petrol to afford the bis(hemiadipate) as a colourless solid (183 mg, 50%); mp 133° C.; 1H NMR (500 MHz, d6-DMSO) δ 1.55-1.70 (m, 8H, CH2CH2), 2.24 (t, 2H, J=7.0 Hz, CH2CO), 2.27 (t, 2H, J=7.0 Hz, CH2CO), 2.63 (t, 2H, J=7.0 Hz, CH2CO), 2.64 (t, 2H, J=7.0 Hz, CH2CO), 7.37 app. d, 2H, J=9.0 Hz, H3′,5′), 7.55 (dd, 1H, J5,6=8.5, J6,7=7.5, Hz, H6), 7.80 (d, 1H, J7,8=8.5 Hz, H8), 7.88 (ddd, 1H, J6,7=7.5, J7,8=8.5, J5,7=1.5 Hz, H7), 7.96 (app. d, 2H, J=9.0 Hz, H2′,6′), 8.08 (dd, 1H, J5,6=8.5, J5,7=1.5 Hz, H5); 13C NMR (125 MHz, d6-DMS) δ 23.77, 23.82, 32.6, 33.2, 33.3; 44.3 (CH2), 118.7, 122.5, 122.6, 122.7, 125.1, 126.8, 129.7, 132.9, 134.8, 152.7, 154.9, 155.1 (Ar), 170.4, 171.1, 171.4, 174.3, 174.3 (5C, C═O); IR 3059, 2940, 2873, 1768, 1706, 1504, 759 cm−1; HRMS (ESI−) m/z 509.1441, C27H25O10 [M−H]− requires 509.1442.
