Stereoselective Synthesis of Highly Functionalized Cyclohexenes via Strong-Acid-Mediated Endocyclic C-C Bond Cleavage of Monocyclopropanated Cyclopentadienes.
Sebastian FischerTerrence-Thang H NguyenAndreas RatzenboeckHuw M L DaviesAnd Oliver ReiserPublished in: Organic letters (2023)
A stereoselective, solvent- and metal-free endocyclic C-C bond cleavage of monocyclopropanated cyclopentadienes mediated by strong acids was developed, leading to highly functionalized six-membered carbocycles with high stereocontrol. The critical step for this ring-expansion is the formation of a cyclopropyl carbocation that undergoes endocyclic ring opening via an SN 2 '-type attack of various nucleophiles. Subsequent synthetic transformations show the versatility of the resulting cyclohexenes for the synthesis of new compounds with nonconventional substitution patterns.
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