MolSynapsequestion bank
MolSynapse / Question bank / Hydrocarbons / Conjugated dienes and Diels-Alder reaction
JEE Main levelSingle correct optionDifficulty 2 of 3hc098

Buta-1,3-diene reacts with dimethyl fumarate (dimethyl (E)-but-2-enedioate). The Diels-Alder adduct is

  1. Adimethyl cis-cyclohex-4-ene-1,2-dicarboxylate (meso)
  2. Bdimethyl trans-cyclohex-4-ene-1,2-dicarboxylate (as a racemate)
  3. Cdimethyl cyclohex-3-ene-1,2-dicarboxylate with the esters in a 1,3 relationship
  4. Ddimethyl cyclohex-4-ene-1,2-dicarboxylate as a mixture of cis and trans isomers in equal amounts

Answer: B

The Diels-Alder reaction is stereospecific and suprafacial on the dienophile: the relative geometry of the substituents is retained. The trans (E) dienophile therefore gives the trans-1,2-diester on the new ring, which is chiral and formed as the racemate. Dimethyl maleate would have given the cis (meso) diester.
Practice Hydrocarbons More on Conjugated dienes and Diels-Alder reaction
Previous questionNext question

More questions on Conjugated dienes and Diels-Alder reaction