Ethyl isopropenyl ether

Diels-Alder reaction, of acrolein with B-butyl cyclohexenyl ether, n-butyl vinyl ether, and ethyl isopropenyl ether, 34, 30... 

Under comparable conditions the submitters found that the corresponding dihydropyran derivatives were similarly obtained by the condensation of acrolein with methyl vinyl ether in 80-81% yield, with ethyl vinyl ether (77-85% yield), with w-butyl vinyl ether (82% yield), with ethyl isopropenyl ether (50% yield), and with w-butyl cyclohexenyl ether (40% yield). Other <, /3-un-saturated carbonyl compounds that have thus been condensed with ethyl vinyl ether are crotonaldehyde (87% yield), meth-acrolein (40% yield), a-ethyh/3-n-propylacrolein (54% yield), cinnamaldehyde (60% yield), /3-furylacrolein (85% yield), methyl vinyl ketone (50% yield), benzalacetone (75% yield), and benzal-acetophenone (74% yield). 

Esters -> vinyl ethers. The original publication (8, 83-84) mentioned that ethyl acetate reacts with 1 to give ethyl isopropenyl ether. More recent work1 has shown that this conversion of esters to vinyl ethers is general and proceeds in high yields. The reaclion rate is dramatically increased by the presence of donor ligands (THF, C,11SN). The solvent is benzene or toluene. Ketone methylenation is possible, and actually Ihc rate is lour times that of ester methylenation. Isolated yields are cited in the examples. 

Ketones can also be converted into their a-isopropenyl derivatives using the complex [C5HsFe(CO)2(ethyl isopropenyl ether)] [BF4]". ... 

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