Abstract
Oxalylacetylenes act as dielectrophiles in the annulation of quinolines to give highly
functionalized 1,3-oxazine cycles decorated with ethynyl, oxalyl, ester and aryl substituents.
The annulation proceeds under mild conditions (room temperature, without catalyst)
in 2:1 mode with respect to acetylene and quinoline to deliver 1,3-oxazinoquinolines
in 45–88% yields. A beneficial feature of the reaction is that, in contrast to results
on the reaction of quinolines with trifluoroacetylacetylenes in the presence of water,
where H2O acted as a third electrophile, leading to the 1,3-oxazinoquinolines containing a
hydroxyl group, this reaction well tolerates the aqueous medium. This reaction also
tolerates isoquinoline and phenanthridine.
Key words
alkynes - quinolines - oxazines - nucleophilic addition - annulation
