Synthesis and polymerization behavior of 2,3-dihydro-1,4-dioxin-2-one and its 3-methyl derivative

The hitherto unknown 2,3-dihydro-1,4-dioxin-2-one ( 7 ) and its 3-methyl derivative 8 have been synthesized for the first time. The olefinic double bond is inserted into the saturated 1,4-dioxanone precursors 3 and 6a/b by a retro-Diels-Alder reaction in the last step of the synthesis. The 1,4-dioxanone systems of 3 and 6 are prepared by reacting a vicinal dialkoxide with α-halogenated acyl halides, thus forming the ester and the ether bond in a one-pot reaction. Monomers 7 and 8 are polymerized by cationic initiation. The resulting products undergo fragmentation to form oligomers in the presence of protic solvents, indicting that ring-opening polymerization of the δ-lactone apparently leads to polyester chain segments.