31. A Diels Alder reaction between two pyridine functionalized substrates normally yield a mixture of endo and exo products. 32. A related popular catalyst scandium triflate is used in such reactions as aldol reactions and Diels-Alder reactions . 33. A hexadehydro Diels-Alder reaction ( HDDA ) involves cycloaddition of 1, 3-diyne and alkyne. 34. Because the diene is very electron-rich it is a very reactive reagent in Diels-Alder reactions . 35. The Diels-Alder reaction of ?-nitrostyrene and cyclopentadiene is described in a number of early papers. 36. Diels-Alder reactions occur between a conjugated diene and an alkene ( commonly known as the dienophile ). 37. A decade later, Elias James Corey introduced an effective aluminum-diamine controller for Diels-Alder reaction . 38. It is produced by the Diels-Alder reaction of two equivalents of hexachlorocyclopentadiene with one equivalent of cyclooctadiene. 39. The Diels-Alder reaction itself is a powerful reaction that can give cyclic compounds with many stereogenic centers. 40. The retro-Diels Alder reaction occurs quickly afterwards to form the stable 1, 2, 3 triazole.
