HCID 68567908, compound → HCID 67928966, compound

Participants

Reaction Steps

A mixture of benzhydryl 3-phenoxymethyl-4-thia-2,6-diazabicyclo[3.2.0]hept-2-ene-7-one-6-isopropenyl acetate, 2, (150 mg., 0.3 mmole) and iodine (127 mg., 0.5 mmols) in methylene chloride (9 ml) was stirred at ambient temperature for 15 mins. Water (9 ml) was then added to the stirred solution and air bubbled through the solution. After a reaction time of 45 mins the reaction mixture was washed with aqueous sodium thiosulfate, then water, and the organic layer dried over magnesium sulfate. Filtration and concentration gave the product as a pale yellow foam. Analysis of the foam by nmr spectroscopy showed a mixture of the 2-methylpenam, 1 (R=φOCH2, R1 =CHφ2, R2 =H, 69.4%), the starting material 2 (16.7%), and the 3-iodocepham, 6 (13.8%). The 2-iodomethylpenam could be isolated by thick layer chromatography. On standing (in solution or as a foam) at room temperature the 2-iodomethylpenam 1 is slowly converted to the thermodynamically more stable 3-iodocepham, 6. If the iodination reaction is allowed to run for longer periods of time, increasing amounts of 6 are obtained and after 10 hrs to a week, the major product is 6.

Provenance & Evidence