P(NMe<sub>2</sub>)<sub>3</sub>-Mediated Umpolung Spirocyclopropanation Reaction of <i>p</i>-Quinone Methides: Diastereoselective Synthesis of Spirocyclopropane-Cyclohexadienones
Yu‐Hua Deng, Wen‐Dao Chu, Yun-Han Shang, Ke‐Yin Yu, Zhi-Long Jia, Chun‐An Fan
Abstract
An unprecedented umpolung spirocyclopropanation reaction of p-quinone methides and α-keto carbonyls is described. Our umpolung strategy based on 1,6-conjugate addition and intramolecular nucleophilic substitution offers a new method for effective access to a series of highly functionalized spirocyclohexadienonyl cyclopropanes having two vicinal quaternary carbons in ≤98% yield and >20:1 dr. Significantly, cyclic and acyclic topological structures of α-keto carbonyls as 1,1-dipole one-carbon synthons have a distinct influence on the stereochemistry of products, showing a reversal of diastereoselectivity in this P(NMe2)3-mediated umpolung spirocyclopropanation.
Topics & Concepts
UmpolungChemistrySynthonNucleophileIntramolecular forceYield (engineering)QuinoneStereochemistryMedicinal chemistryOrganic chemistryCatalysisMetallurgyMaterials scienceSynthesis of Indole DerivativesSulfur-Based Synthesis TechniquesChemical Synthesis and Reactions