11. Diels-Alder reactions occur between a conjugated diene and an alkene ( commonly known as the dienophile ). 12. Partially negative atoms on the diene will bond to partially positive atoms on the dienophile , and vice versa. 13. When the substituents of the dienophile are exo, there is no interaction between those substituents and the diene. 14. This weak acid forms a diester, it undergoes additions across the double bond, and it is an excellent dienophile . 15. For this reason, benzocyclobutadiene will readily dimerize or polymerize and it reacts as a dienophile in Diels-Alder reactions. 16. The relationship is only valid for the groups on the diene alone, or the groups on the dienophile , alone. 17. This is due to the alcohol precursor dehydrating under acidic conditions to produce both the diene and dienophile required for this reaction. 18. A pyranone was similarly used as the dienophile by K . C . Nicolaou's group in the total synthesis of taxol. 19. In intramolecular Diels-Alder Reaction, asymmetric induction can be induced through allylic 1, 3 strain on the diene or the dienophile . 20. One cannot predict, via this principle, whether a substituent on the diene will be syn or anti to a substituent on the dienophile .
