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

Reactions between 1-nitroso-2-naphthols and α-functionalized ketones such as α-bromo-, α-chloro-, α-mesyloxy-, α-tosyloxy-, and α-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 α-functionalized ketones. With aryl bromides, allyl bromides, α-bromo diketones, α-bromo cyanides, α-bromoesters, and α-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%.