All 3 products are mixtures of enantiomers and diastereomers due to the Diels-Alder reaction forming two stereoisomers.
The major product for the following Diels-Alder reactions is a mixture of enantiomers and diastereomers.
The first reaction involves the Diels-Alder cycloaddition of 1,3-cyclopentadiene and maleic anhydride. The product is a racemic mixture of cis- and trans-bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic anhydride. The cis and trans isomers are diastereomers, and the racemic mixture of cis and trans isomers is a mixture of diastereomers.
The second reaction involves the Diels-Alder cycloaddition of 1,3-cyclohexadiene and methyl acrylate. The product is a mixture of cis- and trans-bicyclo[2.2.2]oct-5-ene-2-carboxylic acid methyl ester. The cis and trans isomers are diastereomers, and the mixture of cis and trans isomers is a mixture of diastereomers.
The third reaction involves the Diels-Alder cycloaddition of furan and dimethyl maleate. The product is a mixture of cis- and trans-bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid dimethyl ester. The cis and trans isomers are diastereomers, and the mixture of cis and trans isomers is a mixture of diastereomers.
In all three cases, the major product is a mixture of enantiomers and diastereomers because the Diels-Alder cycloaddition reaction can occur in two different ways, leading to two different stereoisomers. The two stereoisomers are mirror images of each other, and they are enantiomers. The two stereoisomers are also different diastereomers.