An AM1 study on π-facial selectivity in Diels-Alder reactions of 2-aza-1, 3-dienes with azodienophiles

Abstract A theoretical study of the π-facial selectivity in Diels-Alder reactions of chloro derivatives of 2-aza-1,3-dienes with azodienophiles has been carried out using the semiempirical AM1 method. Three transition structures for the model reaction of the diene 3 with the dienophile 4 were located. The Diels-Alder reaction of the non-substituted 2-aza-1,3-diene 6 with the trans -diimide was studied. All transition structures located show an important asynchronicity and the calculations reveal the presence of stereoelectronic effects. The predicted stereoselectivity is in agreement with the experimental evidence.