Vinylketene thioacetals

Vinylketene thioacetals react by a Michael-type addition with an alkyllithium in THF at -80 to —20°. Thus successive addition of n-butyllilhium and methyl iodide to (8) gives the thioacetal of thea,/i-unsaturated methyl ketone (9) in almost quantitative... 

Vinylketene thioacetals.5 2-Lithio-2-trimethylsilyl-l,3-dithiane (1) also reacts with a,/J-unsaturated aldehydes and ketones exclusively with the carbonyl group to give vinylketene thioacetals (2). These undergo Diels-Alder cycloaddition, which Carey and... 

Court have used for a synthesis of a cyclohexenone. Thus the vinylketene thioacetal (3) reacts with maleic anhydride in refluxing xylene (3 hr.) to give the adduct (4) in 60% yield. Hydrolysis of the dithioacetal group was effected with mercuric chloride in 90% aqueous methanol at reflux. The initial product (5), a / -keto acid, undergoes decar-... 

Unfortunately the Diels-Alder reaction of vinylketene thioacetals is limited to reactive dienophiles thus (3) does not react with diethyl maleate or diphenylacetylene. Also several vinylketene thioacetals werefound tobeunreactive toward maleicanhydride. 

Vinylite SYHM resins, SMA sodium derivative, 426 1-Vinylimidazole MA copolymerization, 336 maleates copolymerization, 337 1-Vinylindole, MA copolymerization, 336, 660 -Vinylindole, fumarates copolymerization, 337 Vinylketene thioacetal, MA Diels-Alder adduct, 106, 107... 

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