反应详情

In order to study the contribution of the length of the conjugation bridge to the AR activity, compound Q110 with a four-conjugated-double bond linker and compound Q111 with a five-conjugated-double bond linker were synthesized and illustrated in Scheme 13. Compound Q110 was synthesized starting from 1,2-dimethoxy-4-propyl-benzene. To a solution of 3-(3,4-dimethoxyphenyl) propane in dry dioxane was added with DDQ (3.1 eq.) and catalytic amount of acetic acid. The mixture was sonicated for 2 h with TLC monitoring. After completion of the reaction, the solid was filtered out and the filtration was concentrated. The residue was dissolved in EtOAc and washed with water, 2% NaHCO3, and brine. The organic extract was dried over Na2SO4 and concentrated to afford a crude as yellow-brownish solid, which was purified with neutral alumina column chromatography and eluted with hexanes-ethyl acetate mixture to give a light yellow solid, 3,4-dimethoxycinnamaldehyde in 60% yield (B. P. Joshi et al., Tetrahedron, 62, 2590-2593, 2006). A solution of 2,4-petanedione (3 eq.) and B2O3 (1 eq.) in EtOAc was stirred at 40° C. for 0.5 h, 3,4-dimethoxycinnamaldehyde (1 eq.) and tributyl borane (1 eq.) were added. The resulting reaction mixture was stirred at 40° C. for 0.5 h. Butylamine (1.2 eq.) in EtOAc was added dropwise at the temperature and stirred at 40° C. for 16 h. To the red reaction mixture, 1% HCl aq was added and the mixture was stirred to 60° C. for 1 h. After cooling to rt, the aqueous was separated and the organic was washed with water to pH˜7 and dried over Na2SO4. The crude was purified by silica gel flash column chromatography to get the intermediate product 8-(3,4-Dimethoxy-phenyl)-4-hydroxy-octa-3,5,7-trien-2-one as an off-white solid. A solution of the intermediate (1 eq.) and B2O3 (0.7 eq.) in EtOAc was stirred at 70° C. for 0.5 h. 3,4-dimethoxybenzaldehyde (1 eq.) and trubutyl borane (1 eq.) were added and the reaction mixture was stirred at 70° C. for 0.5 h. Piperidine (1.2 eq.) in EtOAc was added dropwise and the reaction mixture was stirred at 88-90° C. for 1 h. After cooling to 60° C., 1% HCl aq was added and the mixture was stirred at 60° C. for 0.5 h. The reaction mixture was worked-up by following the procedure described above and the crude was purified by silica gel column chromatography to afford the desired product Q110 as a red solid. Amorphous, mp. 65-68° C., ESI MS m/z: 423.1 [M+H]+; 1H NMR (300 MHz, CDCl3) δ: 7.64-7.58 (d, 2H, H-1 and 2), 7.16-7.02 (4H, aromatic ring H and trans double bond H), 6.90-6.82 (4H, aromatic ring H), 6.53-6.48 (1H, trans double bond H), 6.18-6.12 (1H, trans double bond H), 5.75 (s, 1H, H-4), 3.94-3.92 (12H, —OCH3).

1. customwere synthesized
2. customCompound Q110 was synthesized
3. customThe mixture was sonicated for 2 h with TLC monitoring
4. customAfter completion of the reaction
5. filtrationthe solid was filtered out
6. filtrationthe filtration
7. concentrationwas concentrated
8. dissolutionThe residue was dissolved in EtOAc
9. washwashed with water, 2% NaHCO3, and brine
10. extractionThe organic extract
11. dry with materialwas dried over Na2SO4
12. concentrationconcentrated
13. customto afford a crude as yellow-brownish solid, which
14. customwas purified with neutral alumina column chromatography
15. washeluted with hexanes-ethyl acetate mixture