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. ... The Diels-Alder reactions of 1-methoxycarbonyl-4-dimethylamino-2-thiomethyl-1,3-diazabutadiene with dimethyl acetylenedicarboxylate (DMAD) and monophenyl ketene give pyrimidines in one pot. ... Tetrahedron Lett., 29 (1988), p. 921 and references cited therein.