反应详情

To a solution of probucol (5.16 g, 10 mmol) in THF (20 mL) cooled to 0° C. were added triphenylphosphine (1.3 g, 5 mmol), diethyl azodicarboxylate (0.8 mL g, 5 mmol) and 2-ethoxy-1,3-dioxolane-4(S),5(S)-dimethanol (0.89 g, 5 mmol; Nicolaou, K. C. et al.: J. Org. Chem. 1985, 50, 1440–1456). The resultant mixture was stirred at reflux for 3 hours and then evaporated. Silica gel chromatography (hexanes/ethyl acetate 4:1) gave 2,6-di-tert-butyl-4-{1-[3,5-di-tert-butyl-4-(2-ethoxy-5(S)-hydroxymethyl[1,3]dioxolan-4(S)-yl-methoxy)-phenylsulfanyl]-1-methyl-ethylsulfanyl}-phenol in three parts: diasteroisomer A (0.36 g), diastereoisomer B (0.22 g) and a mixture of the two (0.72 g) all as viscous residues (total yield: 39%). Diastereoisomer A: 1H-NMR (CDCl3) δ 7.56 (s, 2H, Ph-H), 7.44 (s, 2H, Ph-H), 5.89 [s, 1H, CH(O) 3], 5.37 (s, 1H, PhOH), 4.7{tilde over (3)}4.81 (m, 1H, PhOCH2CH), 4.1{tilde over (9)}4.25 (m, 1H, CHCH2OH), 3.8{tilde over (0)}4.01 (m, 3H, CH2O), 3.6{tilde over (2)}3.96 (m, 3H, CH2O), 2.80 (dd, J=9, 3, 1H, OH), 1.45 (s, 6H, S,S′-isopropylidene), 1.44 (s, 18H, tert-butyls), 1.43 (s, 18H, tert-butyls), 1.25 (t, 3H, OCH2CH3). Diasteroisomer B: 1H-NMR (CDCl3) δ 7.56 (s, 2H, Ph-H), 7.44 (s, 2H, Ph-H), 5.92 [s, 1H, CH(O) 3], 5.36 (s, 1H, PhOH), 4.5{tilde over (0)}4.59 (m, 1H, PhOCH2CH), 4.1{tilde over (3)}4.30 (m, 3H, CHCH2OH, CH2O), 3.8{tilde over (9)}4.00 (m, 3H, CH2O), 3.61 (quad, J=7, 2H, OCH2CH3), 1.86 (dd, J=6, 8, 1H, OH), 1.4{tilde over (1)}1.46 (m, 42H, S,S′-isopropylidene, tert-butyls), 1.21 (t, 3H, OCH2CH3).

1. temperatureat reflux for 3 hours
2. customevaporated