Question

Provide the major product(s) for the following Diels-Alder reactions. Indicate appropriate stereochemistry if needed using proper dashes or wedges or appropriate perspective. Also, indicate if the product is a racemic mixture of enantiomers, a mixture of diastereomers, or a meso-compound. Indicate the starting materials that could produce the following Diels-Alder product.

Answer 1

CH3 O H2 O CH O In Diels-Alder reaction, stereochemistry is always preserved as it goes through concerted mechanism. Thus the given reaction produces mixture of meso-compounds. CH3 O CH3 O CH3 O CH Both are meso-compounds H3C CH2 H3C CH з НЗС HaC CH H CH CH3 CH H3C 0 CH2 meso-compound CH 0

As shown in left we can do reverse Diels-Alder reaction to give the desired product. The -CN group compound can act as CH NEC-CH2Cc-CH2CEN a dinophile and other can act as a dine CH2 ας CH2 CH2