Stereoelectronic effects in the Stereoselectivity of the Diels-Alder Reactions: Reactions of Aminoanthracenes with N-phenylmaleimide

Ruhima Khan, Anjana Ningombam,

Abstract

Diels-Alder reaction of aminoanthracenes with N-phenylmaleimide gives two stereoisomeric adducts syn (~70%) and anti (~30%) irrespective of the amino group being at 1- or 2- positions of anthracene. The results indicate that electronic effect is dominating in deciding the isomer ratio. The configuration of the adducts syn and anti have been established with the help of spectroscopic data of the adducts and the corresponding N-diacetamido derivatives. Whereas free rotation about the aryl C(2) - N bond is observed in 2-diacetamido derivative, there is hindered rotation and non-planar conformation about the aryl C(1)-N bond in the 1-diacetamido derivative.