Carbonyl compounds, unsaturated sulphonation

In the Diels-Alder reaction, a conjugated diene reacts with an a,P-unsaturated carbonyl compound, generally called a dienophile. A die-nophile is a reactant that loves a diene. The most reactive dienophiles usually have a carbonyl group, but it may also have another electron-withdrawing group, e.g. a cyano, nitro, haloalkene or sulphone group conjugated with a carbon-carbon double bond. 

The selective reduction of ,/3-unsaturated carbonyl compounds can be achieved using a palladium complex, (t-Bu2PH)Pd(t-Bu)2k- pretreated with oxygen53. Vinylic sulphones and phosphates can be reduced selectively to the saturated products using the same remarkable catalyst54 as can double bonds adjacent to epoxides. In the latter case the epoxide remains undamaged55. 

Few studies of /7-toluenesulphonylhydrazones themselves have been reported. The major products of / -tosylhydrazone derivatives of aryl and a,j -unsaturated carbonyl compounds have now been shown to be azines and sulphones, the formation of the former being preferred in benzene and the latter in methanol. 

Michael addition reactions of allyl sulphones and a/3-unsaturated carbonyl compounds provide useful starting points in synthesis, illustrated in a synthesis of chrysanthemate ester [Me2C=CHCH2S02ph -I- Me2C=CHC02R -> MeaC= CHCH(S02Ph)CMe2CH2C02R cis- and tm/is-cyclopropane esters]. ... 

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