Acetone → HCID 56618122, compound

Participants

Reaction Steps

Methyl (5R,6R)-3-[(E)-2-acetamidoethenylthio]-6-[(1S)-1-ethoxysulphonyloxy-ethyl]-7-oxo-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylate (110 mg) in dry dichloromethane (4 ml) was cooled to -70° (acetone/solid CO2 bath) and bromine (0.25 ml of a 1 M solution in CCl4) was added to the stirred solution. After 20 mins, triethylamine (50 mg) in dichloromethane (0.5 ml) was added and stirring was continued at -70° for 15 min. The mixture was allowed to warm to room temperature over 30 min. The solution was then washed with water (2×), dried (MgSO4) and evaporated in vacuo to give a brown oil (130 mg). This was chromatographed on silica gel (10 g; 230-430 mesh ASTM) eluting with ethyl acetate/cyclohexane (8:2) to give, after combination and evaporation of the appropriate fractions, methyl (5R,6R)-3-(2-acetamido-1-bromoethylthio)- 6-[(1S)-1-ethoxysulphonyloxyethyl]-7-oxo-1-azabicyclo[3.2.0.]hept-2-ene-2-carboxylate (39 mg), λmax (EtOH), 310 and 245 nm, νmax (CH2Cl2) 1790, 1720, 1625 cm-1, δ(CDCl3) 1.40 (3H, t, J 7 Hz, CH3CH), 2.12 (3H, s, CH3CO), 3.07 (1H,dd, J1 19 Hz, J2 10 Hz 4-CHAHBCH), 3.39 (1H,dd, J1 19 Hz, J2 9.5 Hz, 4-CHAHBCH), 3.7-3.9 (4H, s, at δ 3.80 superposed on m, OCH3 6-CH), 4.1.-4.5 (3H, q, J 7 Hz at 4.30, superposed on m, OCH2CH3, 5-CH) 4.7-5.2 (1H,m, CH.CH.CH3), 7.42 (1H, broad d, J 11.5 Hz, CONHCH), 7.70 (1H, d, J 11.5 Hz,=CHNHCO).

Provenance & Evidence