[I:1]Cl.[N-:3]=[N+:4]=[N-:5].[Na+].[OH:7][CH2:8][CH:9]([CH2:22][OH:23])[CH2:10][CH2:11][N:12]1[CH:19]=[C:18]([CH:20]=[CH2:21])[C:16](=[O:17])[NH:15][C:13]1=[O:14].C(Cl)(Cl)Cl.CO>C(#N)C>[OH:7][CH2:8][CH:9]([CH2:22][OH:23])[CH2:10][CH2:11][N:12]1[CH:19]=[C:18]([CH:20]([N:3]=[N+:4]=[N-:5])[CH2:21][I:1])[C:16](=[O:17])[NH:15][C:13]1=[O:14]Iodine monochloride (50 mg, 0.3 mmol) was added slowly with stirring during a five minute period to a suspension of sodium azide (72 mg, 1.1 mmol) in dry acetonitrile (10 ml) at ice-bath temperature with stirring. This mixture was stirred for a further 5 min., a solution of 20 (66 mg, 0.275 mmol) in dry acetonitrile (40 ml) was added, the reaction mixture was maintained at 0° C. for 30 min. with stirring. The resulting red-brown colored reaction mixture was poured onto ice cold water (25 ml), the mixture was extracted with ethyl acetate (3×50 ml) and the ethyl acetate extract was washed with 5% aqueous sodium thiosulfate (30 ml). Drying the colorless ethyl acetate fraction (Na2SO4), removal of the solvent in vacuo and purification of the residue obtained by elution from a silica gel column using chloroform:methanol (90:10, v/v) as eluent afforded 21c (24 mg, 21%) as a viscous oil.
Wird geladen…