Effect of the hybridization of the hetero-atom present at the tether on the selectivity of the (3,4)ene cyclization: A theoretical study

Presence of sp2 hybridized atom at the tether of (3,4)ene cyclization alters the diastereoselectivity of the overall reaction. Theoretical investigation on the B3LYP/6-31G∗ optimized transition structures (TSs) of nitrogen tethered (3,4)ene cyclization has been performed to calculate the product proportions. The hybridization of the nitrogen atom is found to be the determining factor to alter the relative energies of the corresponding TSs and thus directs the overall stereoselectivity of the reaction. It appears from the present study that the relative proportion of the 'trans' diastereomeric product will be increased when a sp2 hybridized atom is incorporated into the tether of (3,4)ene cyclization reaction.