207350-17-2Relevant academic research and scientific papers
A robust palladium(II)-Porphyrin complex as catalyst for visible light induced oxidative C-H functionalization
To, Wai-Pong,Liu, Yungen,Lau, Tai-Chu,Che, Chi-Ming
, p. 5654 - 5664 (2013/06/04)
A series of palladium(II)-porphyrin complexes that display dual emissions with lifetimes up to 437μs have been synthesized. Among the four complexes, PdF20TPP is an efficient and robust catalyst for photoinduced oxidative C-H functionalization by using oxygen as terminal oxidant. α-Functionalized tertiary amines were obtained in good to excellent yields by light irradiation (λ>400nm) of a mixture of PdF20TPP, tertiary amine, and nucleophile (cyanide, nitromethane, dimethyl malonate, diethyl phosphite, and acetone) under aerobic conditions. Four examples of intramolecular cyclized amine compounds could be similarly prepared. Comparison of the UV-visible absorption spectra before and after the photochemical reaction revealed that PdF20TPP was highly robust (>95 % recovery). The practical application of PdF20TPP has been revealed by the photochemical reactions performed by using a low catalyst loading (0.01mol %) and on a 10mmol scale. The PdF20TPP catalyst could sensitize photoinduced oxidation of sulfides to sulfoxides in excellent yields. Mechanistic studies revealed that the photocatalysis proceeded by singlet-oxygen oxidation. Long-lived excited states! A series of palladium(II)-porphyrin complexes have been synthesized and found to display long-lived excited states with lifetimes up to 437μs (see scheme). Among these complexes, PdF 20TPP is an efficient and robust catalyst for a broad array of photoinduced oxidative C-H functionalization reactions. PtF20TPP= platinum(II) meso-tetrakis(2,3,4,5,6-pentafluorophenyl)porphyrin.
Additive and Vinylogous Pummerer Reactions of Amido Sulfoxides and Their Use in the Preparation of Nitrogen Containing Heterocycles
Padwa, Albert,Kuethe, Jeffrey T.
, p. 4256 - 4268 (2007/10/03)
The α-thiocarbocation generated from the Pummerer reaction of N-methyl-N-phenyl-2-[2-(toluene-4-sulfinyl)phenyl]acetamide undergoes Friedel-Crafts reaction at the γ-carbon with the tethered aromatic ring. Reductive removal of the phenylthio group from the resulting product using Raney nickel occurs in high yield, and the overall reaction represents a new method for the synthesis of a variety of 3-phenyl-substituted oxindoles. Treatment of the related N-benzyl-N-alkyl amido sulfoxide system with trifluoroacetic anhydride affords tetrahydroisoquinolone derivatives. The product distribution encountered coincides with the rotamer population of the starting amide. When the N-benzyl-N-methyl amide is used, only the normal Pummerer product is formed. In this case, the thionium ion is generated in the wrong conformation for π-cyclization to occur. The corresponding N-tert-butyl amido system, however, exists in a geometric orientation which places the benzylic group in the crucial conformation necessary for π-cyclization, and consequently, the reaction proceeds smoothly. Related cyclization reactions occur in good yield with the corresponding furanyl and cyclohexenyl N-tert-butyl amido sulfoxides. The additive Pummerer reaction of 3-phenylsulfinyl-N-benzyl-N-tert-butylacrylamide gave products derived from both 5- and 6-exo trig cyclizations. Intramolecular electrophilic aromatic substitution via six-membered ring closure ultimately afforded a dihydropyridone. The competitive process involving ipso attack of the aromatic ring on the thionium ion generates a spiro cyclohexadienyl cation that undergoes fragmentation of the adjacent σ-bond. The resulting acyl iminium ion is converted to N-tert-butyl-2-phenyl-3-phenylsulfinylacrylamide upon aqueous workup. Only cyclizations leading to five-membered rings occur with the corresponding indolyl and alkenyl N-tert-butyl amido sulfoxides.
