7661-55-4Relevant articles and documents
Transition metal eight-coordination. IV. Tetrakis(5,7-disubstituted-8-quinolinolato)tungsten(V) salts
Archer, Ronald D.,Bonds Jr., Wesley D.,Pribush, Robert A.
, p. 1550 - 1555 (1972)
Violet, paramagnetic [WQ4]+ ions have been synthesized by a variety of methods and appear to be the first complexes of tungsten(V) possessing four chelate ligands. The 5,7-dichloro-8-quinolinol derivative has been synthesized by the reaction of either K3W2Cl9 or W(CO)6 with excess ligand at elevated temperatures for extended time periods or by treating the corresponding tungsten(IV) inner complex with Cl2, Br2, or HClO4 at room temperature or with additional ligand at elevated temperatures. The 7-bromo-5-methyl-8-quinolinol-tungsten(V) species is rapidly produced in the melt reaction of the ligand with W(CO)6. The [WQ4]X salts, where X- = Cl-, Br-, ClO4-, or Q-, disproportionate in alcoholic or aqueous KOH to WQ4 and tungsten(VI). Electronic transitions of the [WQ4] species consist of several bands in the near-infrared and visible region in addition to the normal ligand spectral transitions. A magnetic moment of 1.7 BM, a 〈g〉 value of 1.872, and a 183W hyperfine splitting of 85 G were observed for the dichloro derivative at room temperature. Low-temperature electron spin resonance spectra exhibit three anisotropic g values indicative of isomerization from the D2d-mmmm isomer found for a related 5-bromo-8-quinolinol-tungsten(IV) chelate.1a.
Catalytic Aerobic Dehydrogenatin of N-Heterocycles by N-Hydoxyphthalimide
Chen, Weidong,Tang, Hao,Wang, Weilin,Fu, Qiang,Luo, Junfei
supporting information, p. 3905 - 3911 (2020/08/10)
Catalytic methods for the aerobic dehydrogenation of N-heterocycles are reported. In most cases, indoles are accessed efficiently from indolines using catalytic N-hydroxyphthalimide (NHPI) as the sole additive under air. Further studies revealed an improved catalytic system of NHPI and copper for the preparation of other heteroaromatics, for example quinolines. (Figure presented.).
A methylation platform of unconventional inert aryl electrophiles: Trimethylboroxine as a universal methylating reagent
Feng, Boya,Yang, Yudong,You, Jingsong
, p. 6031 - 6035 (2020/07/10)
Methylation is one of the most fundamental conversions in medicinal and material chemistry. Extension of substrate types from aromatic halides to other unconventional aromatic electrophiles is a highly important yet challenging task in catalytic methylation. Disclosed herein is a series of transition metal-catalyzed methylations of unconventional inert aryl electrophiles using trimethylboroxine (TMB) as the methylating reagent. This transformation features a broad substrate type, including nitroarenes, benzoic amides, benzoic esters, aryl cyanides, phenol ethers, aryl pivalates and aryl fluorides. Another important merit of this work is that these widespread "inert"functionalities are capable of serving as directing or activating groups for selective functionalization of aromatic rings before methylation, which greatly expands the connotation of methylation chemistry.
