SYNTHESIS AND INTRAMOLECULAR HYDROGEN-BON DING OF SYMMETRICAL DIPYRRYLMETHANES

The title compounds were prepared by converting ethyl 5-methylpyrrore- 2-carboxylates into corresponding 5-methyl substituted pyrroles oxydiz ed by surfuryl chloride, bromine, or lead tetraacetate, and then self- condensed without separation and purification, The H-1 NMR analysis an d molecular conformation computation revealed that strong intramolecul ar hydrogen bondings exist in dipyrrylmethane 4(b) and 4(e)(3,3' subst ituents are formate and acetate esters), while very weak or no intramo lecular hydrogen bonding exists in other dipyrrylmethanes.