An ab initio study of the transition structures for the intramolecular Diels-Alder cycloaddition of the aza diene 6 to give brevianamides A, 1, and B, 2, has been carried out with analytical gradients at ab initio 3-21G and 6-31G* basis sets within Hartree-Fock procedures. The correlation effects have been estimated by using the perturbational approach at MP2 and MP3 levels. The geometry, electronic structure, and transition vector component are qualitatively model independent in this study. An analysis of the geometries and energies of the corresponding transition structures provides an explanation for the fact that brevianamide A, 1, is biosynthesized in larger quantities than brevianamide B, 2, while their respective epimers at C7 are not formed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.