Regioselective Synthesis of Tetrasubstituted Pyrroles by 1,3-Dipolar Cycloaddition and Spontaneous Decarboxylation
作者:Yongju Kim、Jonghoon Kim、Seung Bum Park
DOI:10.1021/ol8022193
日期:2009.1.1
We developed a novel regioselective synthesis of tetrasubstituted pyrroles via the classic 1,3-dipolar cycloaddition of alpha,beta-unsaturated benzofuran-3(2h)-one and azlactones (1) followed by spontaneous decarboxylation. The complete regiochemical control of tetrasubstituted pyrroles was confirmed by the orthogonal synthesis of complementary regioisomers (7a and 7b) simply by using different azlactones (1a and 1b, respectively).
An unprecedented protocol has been developed for the synthesis of 3,4-heterocycle-fused coumarins from 4-aminocoumarins and aurones through iodine-catalyzed cascade reactions. Dihydropyridine-fused coumarin, pyridine-fused coumarin, and pyrrole-fused coumarin derivatives were achieved in good yields with high selectivity when CH3CN, AcOH, and DMSO were used as the solvent, respectively. This protocol