title: Corticosteroid decomposition via a mixed anhydride.
abstract: Oxidation of dexamethasone in an aqueous suspension by air during prolonged storage produces the 17alpha-formyloxy-17beta-carboxylic acid 4. A pathway to 4 is proposed that involves Baeyer-Villiger-type oxidation of keto aldehyde 1 to mixed anhydride 5, followed by intramolecular formyl transfer. Synthetically, acid 3 was reacted with N,N'-carbonyldiimidazole followed by triethylammonium formate in order to generate the transient anhydride 5 en route to an authentic sample of 4.
authors.affiliation: Alcon Research, Ltd., 6201 South Freeway, Fort Worth, Texas 76134, USA. ray.conrow@alconlabs.com
authors.forename: Raymond E
authors.initials: RE
authors.lastname: Conrow
authors.forename: Glen W
authors.initials: GW
authors.lastname: Dillow
authors.forename: Liangqiao
authors.initials: L
authors.lastname: Bian
authors.forename: Liang
authors.initials: L
authors.lastname: Xue
authors.forename: Olga
authors.initials: O
authors.lastname: Papadopoulou
authors.forename: John K
authors.initials: JK
authors.lastname: Baker
authors.forename: Britt S
authors.initials: BS
authors.lastname: Scott