Reaction of 1-Nitroso-2-naphthols with α-Functionalized Ketones and Related Compounds: The Unexpected Formation of Decarbonylated 2-Substituted Naphtho[1,2-d][1,3]oxazoles

Reactions between 1-nitroso-2-naphthols and alpha-functionalized ketones such as alpha-bromo-, alpha-chloro-, alpha-mesyloxy-, alpha-tosyloxy-, and alpha-hydroxy ketones under basic conditions delivered 2-substituted naphtho[1,2-d] [1,3]oxazoles in a single synthetic operation. The product formation was accompanied by the unexpected loss of the C=O group from the alpha-functionalized ketones. With aryl bromides, allyl bromides, alpha-bromo diketones, alpha-bromo cyanides, alpha-bromoesters, and alpha-bromo ketoesters as substrates the formation of naphtho[1,2-d] [1,3]oxazoles was also observed. The transformations were performed in 1,2-dichloroethane or acetonitrile under reflux and gave the corresponding naphthoxazoles with yields ranging between 52% and 85%.