Solvent effects in the Diels-Alder reaction

We discussed some effects of varying the solvent in Chapter 13, and we shall now introduce a remarkable and useful special solvent effect in the Diels-Alder reaction. The reaction does not need a solvent and often the two reagents are just mixed together and heated. Solvents can be used but, because there are no ionic intermediates, it seems obvious that which solvent is unimportant—any solvent that simply dissolves both reagents will do. This is, in general, true and hydrocarbon solvents are often the best. 

Phenyl- and 4-methyl-3//-1,2,4-triazole-3,5(4//)-diones have most commonly been employed, although a series of 4-substituted analogs (R = CH3, Et, r-Bu, Bn, 4-CH3OC H4, 4-N02C6H4, CSHSCH = N) have been prepared and the substituent and solvent effects in the Diels-Alder reactions with a variety of dienes determined27. The unsubstituted parent compound is less stable and as a result has been less frequently used22-24. 

Vidis, A., Ohlin, C.A., Laurenczy, G., Kusters, E., Sedelmeier, G. and Dyson, P.J., Rationalisation of solvent effects in the Diels-Alder reaction between cyclopentadiene and methyl acrylate in room temperature ionic liquids, Adv. Synth. Catal. 347, 266-274 (2005). 

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See also in sourсe #XX -- [ ]

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