alpha-Bromocinnamaldehyde → (Z)-2-Bromo-1-phenylundeca-1-en-4,10-diyn-3-ol

Participants

Reaction Steps

To a solution of 1,7-octadiyne (254.4 mg, 2.4 mmol) in dry THF (50 mL) cooled at −78° C. was added nBuLi (1.6 M in hexanes, 1.5 mL, 2.0 mmol) followed by stirring at the same temperature for 10 minutes. To the previously prepared lithium acetylide solution was added a solution of α-bromocinnamaldehyde Compound 1 (422.0 mg, 2.0 mmol) in dry THF (5 mL) and the resultant mixture was stirred at −78° C. for 15 minutes. The reaction was then quenched with saturated aqueous NH4Cl (20 mL) and extracted with EtOAc (50 mL×2). The combined organic layer was washed with brine, dried over anhydrous MgSO4, filtered, and concentrated under reduced pressure. The residue was purified by flash column chromatography (silica gel, 14 percent EtOAc in hexane) to give 613.1 mg (97 percent) of Compound 7: pale yellow oil; Rf=0.33 (14 percent EtOAc in hexane); IR (neat) 3397 (br), 3294, 2944, 2864, 2232, 2116, 1492, 1430, 1064 cm−1; 1H NMR (300 MHz, CDCl3) δ7.65-7.61 (m, 2H), 7.40-7.29 (m, 3H), 7.24 (s, 1H), 5.07 (br s, 1H), 2.68 (d, J=6.18 Hz, 1H, exchangeable with D2O), 2.34-2.27 (m, 2H), 2.26-2.19 (m, 2H), 1.96 (t, J=2.67 Hz, 1H), 1.74-1.62 (m, 4H); 13C NMR (75 MHz, CDCl3) δ135.4, 129.8, 129.1, 128.9, 126.8, 88.3, 84.8, 79.0, 69.4, 69.3, 61.2, 28.1, 27.9, 19.0, 18.6; MS (+CI) m/z (relative intensity) 318 (M+, 81Br, 4), 316 (M+, 79Br, 4), 220 (100).

Provenance & Evidence