Domino metathesis of 3,6-dihydro-1,2-oxazine: access to isoxazolo[2,3-a]pyridin-7-ones.

[reaction: see text] Strained bicyclic 3,6-dihydro-1,2-oxazine is a reactive substrate in domino metathesis with an external alkene. This general transformation leads to isoxazolo[2,3-a]pyridin-7-one, a versatile scaffold combining chemical functions that could be selectively oxidized or reduced. The synthetic relevance of these domino metathesis products is demonstrated by a straightforward synthesis of a quinolizinone.