Dipolar Cycloaddition Reactions of Dihydropyrimidine-Fused Mesomeric Betaines. An Approach toward Conformationally Restricted Dihydropyrimidine Derivatives<sup>1</sup>
作者:C. Oliver Kappe、Karl Peters、Eva-Maria Peters
DOI:10.1021/jo970121q
日期:1997.5.1
mesomeric thiazinium betaines underwent 1,4-dipolarcycloaddition reaction with electron-rich dipolarophiles such as ynamines or ketene acetals. In general, these cycloadditions show a high degree of regioselectivity, facial selectivity, and exo/endo diastereoselectivity. Intramolecular variations of the above processes involving o-alkenylaryl-tethered dihydropyrimidine-fused isomünchnones lead to