Imidazole → HCID 68774133, compound

Participants

Reaction Steps

To a solution of 4 (270 mg) in dichloromethane (1 ml) was added BF3.DMS complex (800 μl). The mixture was stirred for 1.5 h and then poured into ice-water and extracted with ethyl acetate. The residue thus obtained was triturated with ether/heptane (1/1) to provide 5, (250 mg) as a light rose amorphous solid; Rf 0.27 (heptane/ethyl acetate 8/2). The material was dissolved in DMF (3 ml), imidazole (300 mg) was added followed by t-butyldimethylsilyl chloride. After stirring for 2 h at room temperature the silylation was completed. The reaction was quenched by addition of ice water, followed by extraction of the product with ethyl acetate. Chromatographic purification over a short silica column (heptane/ethyl acetate 9/1) gave 6 (220 mg) as a stiff colourless oil; Rf 0.60 (heptane/ethyl acetate 8/2). NMR (CDCl3) δ 7.12 (1H), 6.62 (1H), 6.18 (1H), 1.03 (s, 3H, 18-CH3), 0.98 (s, 9H, tert.butylsilyl), 0.97, 0.95 (2t, 6H, 7α and 15β ethyl), 0.20 (s, 6H, CH3-silylether).

Provenance & Evidence