69884-89-5Relevant academic research and scientific papers
Photocatalytic decarboxylative alkenylation of α-amino and α-hydroxy acid-derived redox active esters by NaI/PPh3 catalysis
Fu, Ming-Chen,Fu, Yao,Shang, Rui,Wang, Ya-Ting,Zhao, Bin
, p. 2495 - 2498 (2020)
Herein, we report the photocatalytic decarboxylative alkenylation reactions of N-(acyloxy)phthalimide derived from α-amino and α-hydroxy acids with 1,1-diarylethene, and with cinnamic acid derivatives through double decarboxylation, using sodium iodide and triphenylphosphine as redox catalysts. The reaction proceeds under mild irradiation conditions with visible blue light (440 nm or 456 nm) in an acetone solvent without recourse to transition-metal or organic dye based photoredox catalysts. The reaction proceeds via photoactivation of a transiently self-assembled chromophore from N-(acyloxy)phthalimide and NaI/PPh3. Solvation plays a crucial role in the reactivity.
Synthesis, molecular structure, and reactivity of neutral and cationic areneosmium(II) complexes with diarylcarbenes as ligands
Weberndoerfer, Birgit,Henig, Gerhard,Hockless,Bennett, Martin A.,Werner, Helmut
, p. 744 - 758 (2008/10/08)
While the dinuclear compounds [(η6-mes)Os{κ1-OC(O)CF3} (μ-Cl)]2 (2) and [(η6-mes)Os{κ1-OS(O)2 CF3}(μ-Cl)]2 (3), prepared from [(η6-mes)OsCl(η3-C3H5)] (1) and CF3CO2H or CF3SO3H by elimination of propene, are not suitable precursors for the synthesis of osmium carbenes, the bis(trifluoroacetato) derivatives [(η6-arene)Os{κ1-OC(O)CF3} (κ2-O2CCF3)] (4, 9, 10) are useful starting materials. They react with diaryldiazomethanes R2CN2 to give the half-sandwich-type complexes [(η6-arene)Os{κ-OC(O)CF3}2 (=CR2)] (11-17) in good to excellent yields. The bis(tosylato)osmium(II)compounds [(η6-arene) Os{κ1-OS(O)2R} {κ2-O2 S(O)R}] (20, 21; R = p-C6H4CH3) behave differently and upon treatment with Ph2CN2 and PhCHN2 afford tetraphenylethene and a mixture of (E)- and (Z)-stilbene. The reaction of 12-15 and 17 with either Me3SiX or NH4X (X = Cl, Br, I) leads to the replacement of the trifluoroacetato ligands and the formation of the corresponding carbene complexes [(η6-arene)OsX2(=CR2)] (22-31) in 67-91% yield. An exchange of trifluoroacetate for chloride or bromide by using HCl or HBr is also possible. Treatment of [(η6-mes)OsCl2(=CPh2)] (28) with M(acac-[Fn]) (M = Na, Tl; n = 0, 3, or 6) affords the chelate compounds [(η6-mes)OsCl(κ2-acac-[Fn])] (33-35) via elimination of the carbene ligand. Compounds 33-35 are also accessible from [(η6-mes)-OsCl2]2 (19) and Hacac/NEt3 or Na(acac-[Fn]) (n = 3 or 6), respectively. While 14 (arene = mes; R = Ph) and 28 react with C6H5MgBr and CH3MgI only by displacement of trifluoroacetate or chloride for bromide or iodide, the reaction of 14 with CH2=CHMgBr gives the η3-allyl complex [(η6-mes)OsBr(η3-CH2CHCPh2)] (36). A C-C coupling also takes place upon treatment of 14 with CH2=CHOEt, resulting in the formation of the metallacyclic compound [(η6-mes)Os{κ2(C,O)-Ph2CCH=CHOEt} {κ1-OC(O)CF3}] (38). The bis(trifluoroacetato) derivatives 14, 15, and 17 react in acetone with water to afford the diaryl(carbonyl)-osmium(II) complexes [(η6-mes)OsR2(CO)] (39-41). On the basis of a labeling experiment, a mechanism for this unusual C-C cleavage reaction is proposed. The reaction of the dichloro compounds 28 and 29 with PPh3 in the presence of AgPF6 gives the cationic carbene complexes [(η6-mes)OsCl(PPh3)(=CR2)]PF6 (45, 46) in nearly quantitative yields. The molecular structures of 2, 15, 28, 35, and 46 were determined crystallographically.
