Synthesis of 2‐Chlorocyclopropene‐Tethered Diazocarbonyl Compounds and Their Cyclization to Form Poly‐Substituted Phenols

Abstract Herein, we disclose a dual C─F bond functionalization of gem ‐difluorocyclopropenes using a catalytic amount of TiCl 4 . The reaction proceeds through a sequential nucleophilic addition of chloride and silyl diazoenolates to the nonsymmetric cyclopropenium cations generated by the fluoride abstraction. The preferential monofluorocyclopropenium‐titanate(IV) salts enable an efficient halogen transfer within the ion pairs, thus providing the opportunity to accept the addition of another type of nucleophiles. A stable [(PhC 3 HCl) + ] 2 [Ti 4 Cl 12 F 6 ] 2− salt was isolated, and its structure was confirmed by X‐ray crystal diffraction. The chemo‐ and regioselective addition of two different nucleophiles gives vicinal substitution products regardless of the electronic properties of substituents on the gem ‐difluorocyclopropenes and the sizes of nucleophiles. Various 2‐chlorocyclopropene‐tethered diazocarbonyl compounds were prepared with the tolerance of a wide range of functional groups. The synthetic utility of the resultant products was demonstrated by the discovery of a new poly‐substituted phenol synthesis via a Rh(II)‐catalyzed cyclization reaction.