Question

Diels Alder reaction

Draw the Diels Alder reaction between cyclopentadiene and maleic anhydride in ethyl acetate.what would happen if it is run inwater? draw the reaction and explain it.

Answer 1

+ Endo adduct

cyclo pentadience Maleic anhydride Exo adduct

Diels alder reaction involves the 1,4 addition of an alkene to a conjugated diene to form an adduct of six memebered ring. the double bond compound is called the dienohile . the reaction is intiated thermally or by lewis acid catalyst with or without the use of solvents.

Here , the reaction between cyclopentadiene and maleic anhydride is a diels alder concerted mechanism reaction.Concerted mechanism is a process in which there is simultaneous breaking and making of bonds through a six centered transition state with no intermediates . it is a 4pi(symbol) + 2pi cycloaddition addition reaction.

There are two possible modes of addition exo addition and endo addition. when the greater part of the dienophile is under the diene ring in the adduct , it is called endo and in the reverse case , it is called exo. The endo adduct is more stable. This is because the cyclic transition state has further stabilization through secondary pi orbital overlaps for a greater accumulation of double bonds in the endo adduct.