Synthesis of cyclic allyl vinyl ethers using Pt(II)-catalyzed isomerization of oxo-alkynes

Several alkynyl epoxides and one alkynyl allyl alcohol were isomerized to cyclic allyl vinyl ethers (3,4-dihydro-2H-1,4-oxazines) using PtCl₂ as the catalyst. Three of these allyl vinyl ethers were converted to 2-hydroxymorpholine derivatives by hydrolysis and two were converted to piperidine derivatives by thermal Claisen rearrangement.