title: Inverse electron demand Diels-Alder reactions of 1,2,3-triazines: pronounced substituent effects on reactivity and cycloaddition scope.
abstract: A systematic study of the inverse electron demand Diels-Alder reactions of 1,2,3-triazines is disclosed, including an examination of the impact of a C5 substituent. Such substituents were found to exhibit a remarkable impact on the cycloaddition reactivity of the 1,2,3-triazine without altering, and perhaps even enhancing, the intrinsic cycloaddition regioselectivity. The study revealed not only that the reactivity may be predictably modulated by a C5 substituent (R = CO(2)Me > Ph > H) but also that the impact is of a magnitude to convert 1,2,3-triazine (1) and its modest cycloaddition scope into a heterocyclic azadiene system with a reaction scope that portends extensive synthetic utility, expanding the range of participating dienophiles. Significantly, the studies define a now powerful additional heterocyclic azadiene, complementary to the isomeric 1,2,4-triazines and 1,3,5-triazines, capable of dependable participation in inverse electron demand Diels-Alder reactions, extending the number of complementary heterocyclic ring systems accessible with implementation of the methodology.
authors: Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA.
authors: Erin D
authors: ED
authors: Anderson
authors: Dale L
authors: DL
authors: Boger
mesh_terms: D003500:Cyclization; D004583:Electrons; D015394:Molecular Structure; D013237:Stereoisomerism; D014227:Triazines / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D014227:Triazines