Palladium catalyzed alkenylation or alkynylation at C-5 of uracil nucleosides using novel phenylidonium triflate

Dehydrogenative alkenylation of uracils via palladium-catalyzed regioselective C–H activation

“…5-iodo 7 , 5-triflated 8 uracils) and metallated alkenes ( e.g . stannane 1a or boron 9 ). These methods rely on multistep reaction sequences, lack atom economy, and are therefore of low efficiency.…”

Aryl Diazonium versus Iodonium Salts: Preparation, Applications and Mechanisms for the Suzuki–Miyaura Cross‐Coupling Reaction

“…Kim and co‐workers described another mechanism for the cross‐coupling of an uracil iodonium triflate with an alkenylboronic acid, that could explain the singularities observed with unsymmetrical iodonium salts (Scheme ) 67. This mechanism had already been suggested by the group of Moriarty for Heck cross‐couplings but no evidence could be demonstrated 51a.…”

“…Heterocyclic iodonium salts have also been used by Kim and co‐workers to synthesize uracil nucleosides from uracil 5‐iodonium triflate and alkenylboronic acid or ester, at room temperature with good yields (Scheme ) 67…”

Synthesis of Uracil-Iodonium(III) Salts for Practical Utilization as Nucleobase Synthetic Modules

“…In 1998, Kim et al reported the uracil-5-ylphenyliodonium(III) triflates (Figure 1, right) prepared by the reaction of 5-tributylstannylated uracils with aryl(cyano)iodonoium triflate. They also demonstrated the preparation of uracil-5-ylphenyliodonium(III) triflates via the reaction of unfunctionalized uracil with phenyliodine(III) diacetate (PIDA) in the presence of triflic acid, and applied it to the palladium-catalyzed alkenylations [18,19]. Recently, the Gaunt research team prepared heteroaryl-uracil-iodonium(III) triflates using m CPBA ( m -chloroperbenzoic acid) and triflic acid as an oxidant and counterion, respectively, and then utilized these synthesized salts for organocatalytic arylation of aldehydes [20].…”

“…Recently, the Gaunt research team prepared heteroaryl-uracil-iodonium(III) triflates using m CPBA ( m -chloroperbenzoic acid) and triflic acid as an oxidant and counterion, respectively, and then utilized these synthesized salts for organocatalytic arylation of aldehydes [20]. However, the isolation and application of uracil-iodonium(III) salts remained mostly limited to treating triflate ( − OTf) salts [18,19,20,21,22], and the relationship between their stability and the structural feature of uracil-iodonium(III) salts has still not been sufficiently explored. This is likely because of their hygroscopic characteristics causing gradual decomposition, as claimed in previous studies [20].…”