Formal [2 + 2 + 2] Cycloaddition Strategy Based on an Intramolecular Propargylic Ene Reaction/Diels−Alder Cycloaddition Cascade
作者:Julia M. Robinson、Takeo Sakai、Katsuhiko Okano、Takafumi Kitawaki、Rick L. Danheiser
DOI:10.1021/ja1053829
日期:2010.8.18
A formal, metal-free, [2 + 2 + 2] cycloaddition strategy is described based on a cascade of two pericyclic processes. The first step involves an intramolecular propargylic ene reaction of a 1,6-diyne to generate a vinylallene, which then reacts in an inter- or intramolecularDiels-Alderreaction with an alkenyl or alkynyl dienophile. Reactions involving unsymmetrical alkenyl and alkynyl dienophiles
Formal Bimolecular [2 + 2 + 2] Cycloaddition Strategy for the Synthesis of Pyridines: Intramolecular Propargylic Ene Reaction/Aza Diels–Alder Reaction Cascades
作者:Michiko Sasaki、Philip J. Hamzik、Hidaka Ikemoto、Samuel G. Bartko、Rick L. Danheiser
DOI:10.1021/acs.orglett.8b02728
日期:2018.10.5
intramolecular propargylic enereaction in the presence of an azadienophile. Reactions employing ethyl N-(tosyl)iminoacetate furnish an intermediate that undergoes elimination and isomerization upon the addition of DBU. The reaction of the intermediate vinylallene with TsCN leads to the isolation of a 2-sulfonylpyridine that serves as a versatile intermediate undergoing substitution reactions with oxygen and