contrast, the regioselective tandem 5-exo-dig mode intramolecular ringclosure reactions of dibenzyl thiol and selenol having a mono-yne into a triple bond gave the trans-biisobenzothiophene and selenophene as the sole product. However, the similar cyclization of dibenzyl tellurol proceeded in both tandem 5-exo and 6-endo-dig modes to afford the trans-biisobenzotellurophene and ditellurachrysene in good yields