Conversion of 2-Sulfinylated 2-Alkenoate Esters to (2E,4E)-2,4-Alkadienoate Esters by Pyrolysis

Article abstract of DOI:10.1246/bcsj.57.729

Thermal reaction of ethyl (2E)-2-phenylsulfinyl-2-alkenoates (E-2) prepared from aldehydes and ethyl 2-phenylsulfinylacetate have been investigated.Refluxing of E-2 or their Z-isomers in xylene resulted in the formation of ethyl (2E,4E)-2,4-alkanedioates accompanied by ethyl (2E)-4-hydroxy-2-alkenoates.Ethyl 2-cycloalkylidene-2-phenylsulfinylacetates were found to be more susceptible to pyrolysis.The enoate esters (2) undergo migration of their carbon-carbon double bond and then <2,3>sigmatropic rearrangement to benzenesulfenate esters, followed by thermolytic extrusion of a benzenesulfenic acid probably via ethyl(2E)-4-phenylsulfinyl-2-alkenoates to afford ethyl (2E,4E)-2,4-alkadienoates.