Regioselectivity in Hetero Diels-Alder Reactions

Regioselectivity in hetero Diels-Alder reactions can be observed in a simple reaction between a nonsymmetrical heterodiene and an unsymmetrical heterodienophile. A 9 h and easy to implement laboratory experiment is described, in which students can observe the regioselectivity of inverse electron-demand hetero Diels-Alder reactions of an azoalkene with furan or 2,3-dihydrofuran acting as dienophile. This experiment combines synthesis, structural analysis (IR spectroscopy and NMR spectroscopy), and dry- and vacuum-flash isolation methods.