Water → HCID 70172017, compound

Participants

Reaction Steps

n-Butyllithium (28.5 mL of a 2.5 M hexane solution, 71.3 mmol) was added dropwise to a slurry of 2,5-bis(triphenylmethylenephosphonium)-1,4-dimethoxybenzene (26.8 g, 35.2 mmol) in dry THF (450 mL) at −78° C.; the reaction mixture immediately became very dark. The cooling bath was removed and the reaction mixture was allowed to warm to room temperature over 2 h before recooling to −78° C. and adding a solution 4-(m-tolylphenylamino)benzaldehyde (21.2 g, 73.8 mmol) in dry tetrahydrofuran (100 mL) dropwise. The reaction mixture was allowed to warm to room temperature and then stirred at room temperature for 2 h before cautiously adding water (300 mL). The mixture was extracted with diethyl ether until the extracts were almost colorless and the combined ether layers were dried on magnesium sulfate. After filtration silica gel was added and the solvent removed under reduced pressure leaving the product absorbed onto the silica. The crude product was transferred to the top of a silica gel column which was eluted with toluene. The first fraction was found to be an approximately statistical mixture of the geometric isomers of 3,5-bis[4-(m-tolylphenylamino)styryl]-1,4-dimethoxybenzene. Further elution gave a trace of an unidentified material, possibly impure 1-[4-(m-tolylphenylamino)phenyl]-pentan-1-ol on the basis of its 1H NMR spectrum, and then 4-(m-tolylphenylamino)benzaldehyde. The mixed isomers were dissolved in toluene (1 L) and heated under nitrogen with a few crystals of iodine. After 48 h, the solution was passed through a silica plug. The solvent was removed under reduced pressure and the solids were recrystallized from hot toluene to afford the pure E,E isomer as a bright yellow powder (12.82 g, 18.2 mmol, 52%). 1H NMR (CD2Cl2) δ 7.43 (d, J=8.6 Hz, 4H), 7.36 (d, J=16.5 Hz, 2H), 7.27 (t, J=ca. 8 Hz, 4H), 7.19-7.00 (m, ca. 16H), 6.94 (br s, 2H), 6.91-6. (br m, 4H) 3.91 (s, 6H), 2.27 (s, 6H); 13C NMR (75 MHz, CD2Cl2) δ 151.7, 148.0, 147.8, 147.7, 139.6, 132.2, 129.5, 129.4, 128.5, 127.6, 126.7, 125.7, 124.7, 124.4, 123.7, 123.2, 122.2, 121.6, 109.0, 56.6, 21.5; UV (THF) λmax 305 (ε305 37000), 426 (ε426 84000) nm; m.p 254° C.; High resolution EIMS calcd. for C50H44N2O2 M+ 704.3403. found 704.3404. Anal. calcd for C50H44N2O2: C, 85.20; H, 6.29; N, 3.97. Found: C, 85.44; H, 6.40; N, 3.86.

Provenance & Evidence