Catalytic Intramolecular Coupling of Ketoalkenes by Allylic C(<i>sp</i><sup>3</sup>)−H Bond Cleavage: Synthesis of Five‐ and Six‐Membered Carbocyclic Compounds
Tsuyoshi Mita, Masashi Uchiyama, Yoshihiro Sato
Abstract
Abstract In the presence of a catalytic amount of cobalt(II) acetylacetonate/Xantphos in combination with trimethylaluminum, various ketoalkenes underwent an intramolecular cyclization reaction triggered by cleavage of the allylic C( sp 3 )−H bond, affording carbocyclic compounds with high regio‐ and diastereoselectivity. Mono‐, bi‐, and tricarbocyclic compounds were produced in good yields. One of the products thus obtained was derivatized into tramadol in four simple steps. Notably, these intramolecular cyclizations took place in the absence of a gem ‐disubstituent on the tethered carbon chain (without the Thorpe‐Ingold effect). magnified image
Topics & Concepts
ChemistryIntramolecular forceAllylic rearrangementXantphosBond cleavageCatalysisMedicinal chemistryStereochemistryCleavage (geology)Intramolecular reactionOrganic chemistryPalladiumGeotechnical engineeringEngineeringFracture (geology)Catalytic C–H Functionalization MethodsSynthesis and Catalytic ReactionsCyclopropane Reaction Mechanisms