1034979-63-9Relevant academic research and scientific papers
Base-promoted selective aryl C-Cl cleavage by iridium(III) porphyrins via a metalloradical ipso addition-elimination mechanism
Cheung, Chi Wai,Chan, Kin Shing
, p. 4999 - 5009 (2011/11/04)
Base-promoted aryl carbon-chlorine bond (Ar-Cl) cleavage by iridium(III) porphyrin carbonyl chloride (IrIII(ttp)(CO)Cl; ttp = 5,10,15,20-tetrakis(p-tolyl)porphyrinato dianion) was achieved in the presence of K2CO3 to give iridium(III) porphyrin aryls (Ir III(ttp)Ar). Mechanistic studies revealed that K2CO 3 promotes the reduction of Ir(ttp)(CO)Cl to give the iridium(II) porphyrin dimer intermediate [IrII(ttp)2. [Ir(ttp) 2 is the source of IrII(ttp) metalloradical, which cleaves Ar-Cl to give Ir(ttp)Ar and a chlorine radical (Cl?) via radical ipso substitution in an addition-elimination pathway. Cl ? reacts with [Ir(ttp)2 to yield Ir(ttp)Cl for subsequent base-promoted reduction and Ir(ttp) for radical chain propagation. Additionally, the base-promoted Ar-Cl cleavage of chlorobenzene (PhCl) by Ir(ttp)(CO)Cl gives both Ir(ttp)Ph and 1,4-bis-iridium(III)-porphyrin benzene, IrIII(ttp)(p-C6H4)IrIII(ttp). The reactive Cl? can simultaneously react with PhCl via homolytic aromatic substitution to give 1,4-dichlorobenzene, which further undergoes double Ar-Cl cleavage to form Ir(ttp)(p-C6H4)Ir(ttp).
Base-promoted selective aryl carbon-bromine bond cleavage by Iridium(III) porphyrin for Iridium(III) porphyrin aryl synthesis: A metalloradical Ipso addition-elimination mechanism
Cheung, Chi Wai,Chan, Kin Shing
, p. 1768 - 1771 (2011/06/22)
K2CO3 was found to promote selective aryl carbon-bromine bond (Ar-Br) cleavage by a high-valent iridium(III) porphyrin carbonyl chloride (IrIII(ttp)(CO)Cl, ttp = 5,10,15,20-tetra-p- tolylporphyrinato dianion) in benzene so
Base-promoted selective aryl C-Br and C-I bond cleavage by iridium(III) porphyrin: Reduction of IrIII-OH to IrII for metalloradical ipso substitution of aryl-halogen bonds
Cheung, Chi Wai,Chan, Kin Shing
experimental part, p. 4269 - 4283 (2011/10/03)
Base-promoted selective aryl carbon-bromine and carbon-iodine bond (Ar-X, X = Br, I) cleavage by iridium(III) porphyrin carbonyl chloride (Ir III(ttp)(CO)Cl) was achieved in the presence of base (K 2CO3, NaOH) to give iridium(III) porphyrin aryls (Ir III(ttp)Ar). Mechanistic studies revealed that the base undergoes ligand substitution with Ir(ttp)(CO)Cl to yield an iridium(III) hydroxo species (IrIII(ttp)OH). The hydroxo ligand most likely reduces the Ir(III) center to give iridium(II) porphyrin dimer ([IrII(ttp)]2) and H2O2. In a competitive pathway, [Ir II(ttp)]2 disproportionates in the presence of base and residual water to give an iridium(III) hydride (IrIII(ttp)H) and Ir(ttp)OH. In a productive process, [Ir(ttp)]2 undergoes Ir II(ttp) metalloradical-mediated ipso substitution of Ar-X via an addition-elimination pathway to form Ir(ttp)Ar and Ir(ttp)X. Ir(ttp)X is recycled by reacting with base to regenerate [Ir(ttp)]2 for subsequent Ar-X cleavage.
