反应详情

Oxalyl chloride (0.37 ml) was added to a solution of N,N-dimethylformamide (0.38 ml) in methylene chloride (10 ml) at -20° with stirring. After five minutes at 0°, the mixture was recooled to -20° and (Z)-2-cyclopropylmethoxyimino-2-(2-tritylaminothiazol-4-yl)acetic acid (1.94 g) was added. The solution was stirred at 0° for ten minutes before recooling to -20°. A slurry of diphenylmethyl (6R,7R)-7-amino-3-carbamoyloxymethylceph-3-em-4-carboxylate (1.76 g) in methylene chloride (10 ml) containing N,N-dimethylaniline (1.26 ml) was added. The solution was allowed to warm to 21° and was stirred for 1.5 hours. After dilution with methylene chloride, the solution was washed with dilute hydrochloric acid and water, each time back-extracting with methylene chloride. The combined organic layers were dried (magnesium sulphate) and concentrated. The solution was loaded into a column of Sorbsil U30 (70 g) which was eluted with a gradient of ethyl acetate (10 to 100%) in petroleum ether (b.p. 40°-60°). Evaporation of the appropriate eluate gave the title compound (3.03 g) as a foam, [α]D21 +10.7° (c 1.03, CHCl3); νinfl 238.5 nm (E1 cm1% 2.78), 258.5 (E1 cm1% 227), 264.5 (E1 cm1% 212), 271.5 (E1 cm1% 186) and 296.5 (E1 cm1% 88)

1. customwas recooled to -20°
2. stirringThe solution was stirred at 0° for ten minutes
3. custombefore recooling to -20°
4. additionwas added
5. temperatureto warm to 21°
6. stirringwas stirred for 1.5 hours
7. washAfter dilution with methylene chloride, the solution was washed with dilute hydrochloric acid and water
8. extractioneach time back-extracting with methylene chloride
9. dry with materialThe combined organic layers were dried (magnesium sulphate)
10. concentrationconcentrated
11. wash(70 g) which was eluted with a gradient of ethyl acetate (10 to 100%) in petroleum ether (b.p. 40°-60°)
12. customEvaporation of the appropriate eluate