Tetrahydrofuran → [3-(2-Ethoxycarbonyl)indolyl]acetaldehyde

Participants

Reaction Conditions

Reaction Steps

A suspension of 11.95 g (34.9 mmol) of methoxymethyltriphenylphosphonium chloride in 200 ml of anhydrous tetrahydrofuran was cooled to 0° C. under N2 atmosphere and treated dropwise with 14.3 ml (35.8 mmol) of n-butyllithium. The resulting solution was stirred for 15 min, treated with 3.70 g (17 mmol) of the resultant compound of Example 97, and stirred at ambient temperature for 3 h. After concentration of the solvent in vacuo, and the residue was taken up in ethyl acetate, washed sequentially with water and saturated brine, dried over MgSO4, and concentrated. The crude mixture of vinyl ethers was partially purified by silica gel chromatography using 6:1 hexane:ethyl acetate. The mixture (2.98 g, 71%) was subsequently treated with 20 ml of 1M HCl and 40 ml of tetrahydrofuran and heated at reflux for 6 h. After cooling, the solution was partitioned between ether and saturated aqueous NaHCO3, dried over MgSO4, and concentrated. Purification by silica gel chromatography using 4:1 hexane:ethyl acetate gave 1.35 g (48%) of the desired compound which was recrystallized from ethyl acetate/hexane. 1H NMR (CDCl3) δ 1.42 (t,J=7 Hz,3H), 4.17 (d,J=2 Hz,2H), 4.42 (q,J=7 Hz,2H), 7.19 (ddd,J=8,7,1 Hz,1H), 7.37 (ddd,J=8,7,1 Hz), 7.43 (br d,J=8 Hz,1H), 7.61 (br d,J=8 Hz,1H), 8.94 (br s,1H), 9.73 (t,J=2 Hz,1H). Mass spectrum: (M+H)+ =232.

Provenance & Evidence