Photochemical cross coupling of alkyl cobaloximes with maleic anhydrides and PhSSPh led to addition of an alkyl moiety and an SPh moiety across the alkene. Oxidation of the sulfide to a sulfoxide followed by elimination of phenyl sulfenic acid provided substituted maleic anhydrides. Alkyl cobaloximes could also be coupled with maleic anhydrides in the absence of PhSSPh to provide substituted maleic anhydrides directly. These methods are applied to a short and efficient synthesis of the anhydride of the Ras farnesyl protein transferase inhibitor chaetomellic acid A and in preparations of C-glycosyl maleic anhydrides, in which the carbohydrate anomeric carbon is directly attached to a maleic anhydride alkene carbon, in modest yields (19-46%).
ASJC Scopus subject areas
- Organic Chemistry