5-Dialkylamino-4-pyrrolin-3-ones, available from cyclocondensation of amidines with dimethylacetylenedicarboxylate (DMAD), undergo rapid singlet oxygenation to give highly functionalized ureas by way of a 1,2-dioxetane cleavage of the initially formed [2 + 2] cycloadducts. These latter compounds undergo cyclization to 2-oxazolidinones in MeOH. Catalytic hydrogenation of the ureas in EtOAc gives 2-oxazolinones
Cyclocondensation of amidines with dimethyl acetylenedicarboxylate: A convenient entry into tetramic acids
作者:Ihsan Erden、Galip Ozer、Christophe Hoarau、Weiguo Cao
DOI:10.1002/jhet.5570430220
日期:2006.3
Amidines undergo cyclocondensations with dimethylacetylenedicarboxylate (DMAD) to give highly functionalized 5-dialkylamino-4-pyrrolin-3-ones. The products are crystalline, highly colored compounds that are uniquely functionalized and represent advanced intermediates in the construction of several other heterocyles, in particular the biologically active tetramicacids. The synthetic transformations