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. ... Preparation and acid-catalyzed Diels-Alder cyclizations of a 1-alkenyl-2-aza- 1,3-diene have been explored. ... Preparation and acid-catalyzed (BF 3 or HBF 4 Diels-Alder cyclizations of a 1-alkynyl-2-aza-1,3-diene ahve been explored. ... (b) Chen, SF; Ho, E.; Mariano, ...