Download full text in PDF Opens in a new window. Article suggestions will be shown in a dialog on return to ScienceDirect. ... Please enable JavaScript to use all the features on this page. ... 3-(3-Butynyloxy)- and 3-(4-pentnyloxy)-1,2,4-triazines undergo facile intramolecular Diels-Alder reactions to yield 2,3-dihydrofuro(2,3- )pyridines and dihydropyrano(2,3- )pyridines respectively. The former are readily dehydrogenated with DDQ to furo(2,3- )pyridines.