Iron (III) Perchlorate Adsorbed on Silica Gel: A Reagent for Organic Functional Group Transformations

Adsorption of Fe(ClO₄)₃(H₂O)₆ onto chromatographic‐grade silica gel in the presence of organic solvents (S=water, acetonitrile, or lower fatty acids) produces a supported reagent, Fe(ClO₄)₃(S)₆/SiO₂. This reagent has been found to be effective for the rapid organic functional group transformations such as dimerization of alkynes, aromatic hydrocarbons, selective oxidation of thiols to disulfides, and transannular reactions in 1,5‐cyclooctadienes on grinding using pestle and mortar in the solid state.     

A Tunable Trifluoromethyliodonium Reagent

Four complexes of MCl₄ (M=Ti, Zr, Hf) with the hypervalent trifluoromethyl iodine reagent trifluoromethyl‐1,3‐dihydro‐3,3‐dimethyl‐1,2‐benziodoxole ( 1 ,=L) are described. With TiCl₄, an I?O bond cleavage occurs, leading to the formation of the trifluoromethyliodonium alcoholate complexes [Ti₂Cl₆(L)₄]Cl₂ ( 2 a ) and Ti₂Cl₈(L) ( 2 b ). Reactions with ZrCl₄ and HfCl₄ form the complexes ZrCl₄(L)₂ ( 3 ) and HfCl₄(L)₂ ( 4 ), respectively, wherein the original I?O bond is retained and elongated compared to that in free 1 . Therefore, the reactivity of 1 can be easily and practically fine‐tuned by addition of different metal chlorides, following the order ZrCl₄/HfCl₄<TiCl₄<2 TiCl₄. Complexes 2 a , 3 , and 4 are remarkably bench‐stable forms of activated reagent 1 , while 2 b is readily accessible in situ. 2 a and 2 b represent the first “real” trifluoromethyliodonium reagents derived from iodanes, that is, with the I?O bond being completely cleaved. The new complexes were shown to be useful for the trifluoromethylation of para‐toluenesulfonate under aprotic conditions.     

PhSO2SCF2H: A Shelf‐Stable,Easily Scalable Reagent for Radical Difluoromethylthiolation

A new shelf‐stable and easily scalable difluoromethylthiolating reagent S‐(difluoromethyl) benzenesulfonothioate (PhSO₂SCF₂H) was developed. PhSO₂SCF₂H is a powerful reagent for radical difluoromethylthiolation of aryl and alkyl boronic acids, decarboxylative difluoromethylthiolation of aliphatic acids, and a phenylsulfonyl‐difluoromethylthio difunctionalization of alkenes under mild reaction conditions.     

PhSO2SCF2H: A Shelf‐Stable,Easily Scalable Reagent for Radical Difluoromethylthiolation

A new shelf‐stable and easily scalable difluoromethylthiolating reagent S‐(difluoromethyl) benzenesulfonothioate (PhSO₂SCF₂H) was developed. PhSO₂SCF₂H is a powerful reagent for radical difluoromethylthiolation of aryl and alkyl boronic acids, decarboxylative difluoromethylthiolation of aliphatic acids, and a phenylsulfonyl‐difluoromethylthio difunctionalization of alkenes under mild reaction conditions.     

FTIR, 1H NMR,ESR, TGA and DTA Analysis of Trithiocarbonates of Captopril and 6‐Mercaptopurine as Their Palladium(II) Chloride Complexes

A simple and sensitive spectrophotometric method has been developed for the determination of the antihypertensive drug captopril and anticancer drug 6‐mercaptopurine, in their trithiocarbonate (TTC) form by using Pd(II) chloride as a coloring reagent. Captopril TTC forms a stable dark yellow colored complex with λ_max 383 nm, molar absorption coefficient 1.35 × 10⁵ l/mole/cm and a Beer's law range from 0.084‐1.26 ppm. 6‐Mercaptopurine TTC forms a stable deep yellow colored complex with λ_max 345 nm, molar absorption coefficient 6.9 × 10⁵ l/mole/cm and a Beer's law range from 0.0319 ppm to 3.519 ppm. The M: L ratio of palladium: TTC complexes were confirmed by Job's method of continuous variance and mole ratio method and was found to be 1:1 for both captopril TTC as well as 6‐mercaptopurine TTC. In addition, on the basis of, FTIR, ¹H NMR, ESR and thermal analysis data a plausible structure of mononuclear Pd(II) complex of Captopril TTC and 6‐mercaptopurine TTC has been reported.     

The Characterization of a New Reagent and Its Application in Determining Cu2+

The study of the reaction of the new spectrophotometric reagent with Cu²⁺, N-allyl-N′-(sodium p-aminobenzenesulfonate)-thiourea(ASAT)'s preparation and its characteristics are described. It was found that this reagent can react with some ions having characteristic phenomena, and, also determine a microamount of copper (?_{303 nm} = 2.39 × 10⁵ L·mol^?1·cm^?1) in aqueous solution. The method's sensitivity and selectivity are good. The new methods are simple and convenient and can provide satisfactory results on samples.     

Aminoazanium of DABCO: An Amination Reagent for Alkyl and Aryl Pinacol Boronates

The aminoazanium of DABCO (H₂N‐DABCO) has been developed as a general and practical amination reagent for the direct amination of alkyl and aryl pinacol boronates. This compound is stable and practical for use as a reagent. Various primary, secondary. and tertiary alkyl?Bpin and aryl?Bpin substrates were aminated to give the corresponding amine derivatives. The amination is stereospecific. The anti‐Markovnikov hydroamination of olefins was easily achieved by catalytic hydroboration with HBpin and in subsequent situ amination using H₂N‐DABCO. Moreover, the combination of 1,2‐diboration of olefins, using B₂pin₂, with this amination process achieved the unprecedented 1,2‐diamination of olefins. The amination protocol was also successfully extended to aryl pinacol boronates.     

Cyclic Amine/Borane Lewis Pairs by the Reaction of N,N‐Diallylaniline with Lancaster′s H2B‐C6F5 Reagent

Twofold hydroboration of N,N‐diallylaniline with the C₆F₅BH₂?SMe₂ reagent gave the respective hetero‐bicyclo[3.3.0]octane and hetero‐methylbicyclo[3.2.0]heptane compounds 4 and 5 as the major products, both showing strong internal N‐B amine Lewis base/borane Lewis acid adduct formation. A DFT analysis indicated their formation (and that of a small amount of several isomeric five‐membered heterocyclic products) under thermodynamic control. Compound 5 underwent fragmentation with propene liberation to form compound 7 with a formal N=B bond at 100 °C. This product was also obtained from the isomer 4 at much higher temperature (300 °C).     

A Novel Fluorescent Reagent for Analysis of Hydrogen Peroxide

IntroductionTheoxidationofmanyclinicalsubstancesinbodyfluidsproducesaquantityofhydrogenperoxide ,sothedetermina tionoftracehydrogenperoxideisofconsiderableimportanceinclinicalchemistry .1Further,themonitoringofhydrogenperoxideisalsonecessarytoenvironmentalsciencesinceitisakeyspeciesinthereactionsofthetroposphere,beingin volvedinimportantreactionssuchasthecatalyzedoruncat alyzedaqueousphaseoxidationofSO2 andtheultraviolet en hancedaqueousphaseoxidationoforganicspecies.2 Uptonow ,variousmethods…     

PEG‐N2O4 System as an Efficient Reagent both for the Rapid Oxidation of Urazoles and 1,4‐Dihydropyridines under Nonaqueous Conditions

N₂O₄ was easily impregnated on polyethyleneglycol to give a stable reagent. Polyethyleneglycol‐N₂O₄ ( PEG‐N₂O₄ ) system was used as an effective oxidizing agent for the oxidation of urazoles and bis‐urazoles to their corresponding triazolinediones and also for the aromatization of 1,4‐dihydropyridines into the corresponding pyridine derivatives under mild conditions at room temperature with good to excellent yields.     

Multiple Pentafluorophenylation of 2,2,3,3,5,6,6‐Heptafluoro‐3,6‐dihydro‐2H‐1,4‐oxazine with an Organosilicon Reagent: NMR and DFT Structural Analysis of Oligo(perfluoroaryl) Compounds

The reagent Me₃Si(C₆F₅) was used for the preparation of a series of perfluorinated, pentafluorophenyl‐substituted 3,6‐dihydro‐2H‐1,4‐oxazines ( 2 – 8 ), which, otherwise, would be very difficult to synthesize. Multiple pentafluorophenylation occurred not only on the heterocyclic ring of the starting compound 1 (Scheme), but also in para position of the introduced C₆F₅ substituent(s) leading to compounds with one to three nonafluorobiphenyl (C₁₂F₉) substituents. While the tris(pentafluorophenyl)‐substituted compound 3 could be isolated as the sole product by stoichiometric control of the reagent, the higher‐substituted compounds 5 – 8 could only be obtained as mixtures. The structures of the oligo(perfluoroaryl) compounds were confirmed by ¹⁹F‐ and ¹³C‐NMR, MS, and/or X‐ray crystallography. DFT simulations of the ¹⁹F‐ and ¹³C‐NMR chemical shifts were performed at the B3LYP‐GIAO/6‐31++G(d,p) level for geometries optimized by the B3LYP/6‐31G(d) level, a technique that proved to be very useful to accomplish full NMR assignment of these complex products.     

Chemical Oxidative Degradation of Acridine Orange Dye in Aqueous Solution by Fenton's Reagent

Degradation of acridine orange (AO) in aqueous solution by Fenton's reagent (Fe²⁺ and H₂O₂) was investigated. The effects of different reaction parameters such as initial AO concentration, pH value of solution, ferrous concentration, hydrogen peroxide concentration, and the presence of chloride ion on the oxidative degradation of AO were investigated. Under optimum conditions, 2 mM H₂O₂, 0.4 mM Fe²⁺ and pH 3.0, the initial 0.2 mM AO solution was reduced by 95.8% within 10 min. The primary intermediates of the degradation reaction of AO were identified. The analytical results indicated that the N‐de‐methylation degradation of AO dye took place in a stepwise manner to yield mono‐, di‐, tri‐, and tetra‐N‐de‐methylated AO species generated during the Fenton process. The probable degradation pathways were proposed and discussed.     

Inside Cover

The inside cover picture shows a dehydrative glycosylation mediated by 2‐aryl‐1,3‐dithiane 1‐oxides. Upon activation of the sulfoxide of the reagent with Tf₂O, a temporary leaving group is installed on 1‐OH sugar, which undergoes a comproportionation reaction to deliver the oxocarbenium ion, thus facilitates the glycosylation reaction. In the picture, the ring formed by two great egrets represents the important cyclic 1,3‐dithiane 1‐oxides dehydrative reagent. This picture was captured in Xiangshan town, Nanchang, Jiangxi Province of China by Mr. Yuguo Chen. More details are discussed in the article by Wan et al. on page 43—49.

     

A Modified Procedure for the Preparation of Cp2Zr(H)Cl (Schwartz's Reagent)

A convenient method for the preparation of 65–85 g quantities of Cp₂Zr(H)Cl, Schwartz's reagent has been developed. The reagent prepared by this method is of high purity and has several advantages over the reagent prepared by previously reported methods.     

Oxidative addition of 1,4‐dichloro‐2‐butyne to an organoplatinum complex: A new precursor for synthesis of ultrasmall Pt nanoparticles thin film at liquid/liquid interface as the electrocatalyst in methanol oxidation reaction

In this study, the usage of ClCH₂CCCH₂Cl alkyne as a reagent for the oxidative addition reaction with organoplatinum?(II) complex [PtMe₂(bipy)] ( 1 ), in which bipy = 2,2′‐bipyridine to give a mixture including of trans‐[PtClMe₂(CH₂CCCH₂Cl)(bipy)] ( 2a ) and a cis‐[PtClMe₂(CH₂CCCH₂Cl)(bipy)] ( 2b ) complexes is reported. Kinetic study was investigated by monitoring the disappearance of the metal‐to‐ligand charge transfer (MLCT) band in the UV–Vis spectra. ¹H NMR experimental results confirmed that trans isomer ( 2a ) is more stable than its corresponding cis isomer. A liquid–liquid planar interface has been employed as a template for self‐assembly of platinum nanoparticles. The as prepared complex was applied for the synthesis of platinum thin film that characterized by transmission electron microscopy (TEM), X‐ray diffraction (XRD), energy dispersive analysis of X‐rays (EDAX), field emission‐scanning electron micrographs (FE‐SEM) and elemental mapping. The electrocatalytical activity of Pt thin film was investigated in methanol oxidation reaction.     

Highly active titanium(IV) dichloride FI catalysts bearing a diallylamino group for the synthesis of disentangled UHMWPE

A family of 16 salicylaldarylimine titanium(IV) dichloride complexes bearing diallylamino group, namely {2‐[3‐ or 4‐(CH₂?CH? CH₂)₂NC₆H₄N?CH]‐6‐R¹‐4‐R²‐C₆H₂O}₂TiCl₂ (R¹ = t‐Bu, CMe₂(Ph); R² = H, Me, OMe, t‐Bu) have been used for polymerization of ethylene in the presence of methylaluminoxane. The effects of reaction conditions on the polymerization were examined in detail. All the pre‐catalyst are highly active (up to 14.0 × 10⁶ g_(PE) mol_(Ti)^{?1 ?1} h^?1) for ethylene polymerization at 30°С to 60°С with the activities and MM correlating with the R¹‐substituent type and position of NAll₂‐group: CMe₂(Ph) > t‐Bu and meta‐NAll₂ > para‐NAll₂ for any R². Highly linear polyethylenes (T_m's as high as 141.0°С) can be obtained with high molecular weights in the range 0.70 to 4.10 × 10⁶ g mol^?1 with disentangled morphology, suitable for technologically more advanced and greeny way to produce high‐modulus high‐strength fibers of ultrahigh molecular weight polyethylene via solid‐state (solvent‐free) deformation processing.     

Cover Picture: A Stepwise Annulation for the Transformation of Cyclic Ketones to Fused 6 and 7‐Membered Cyclic Enimines and Enones (Chin. J. Chem. 4/2019)

The cover picture shows a typical building within the Campus of Xiamen University displaying Chen Jiageng (Tan Kah Kee)'s style. Just like many beautiful buildings designed and constructed by human, Nature “designs and constructs” a huge number of useful molecules with fascinating structures called natural products. Many natural products possess a fused six or seven‐membered carbocyclic unity. On page 315–322, the Huang's group disclosed a three‐step “[2+n]” annulation method for the construction of fused six and seven‐membered carbocyclic enimines and enones. The method starts from simple cyclic ketones and terminal olefinic amides, and relies on both the Suzuki coupling reaction and the olefin‐amide based Friedel‐Crafts type acylating reaction, a method developed by Huang and coworkers.

     

NHC→SiCl4: An Ambivalent Carbene‐Transfer Reagent

The addition of BCl₃ to the carbene‐transfer reagent NHC→SiCl₄ (NHC=1,3‐dimethylimidazolidin‐2‐ylidene) gave the tetra‐ and pentacoordinate trichlorosilicon(IV) cations [(NHC)SiCl₃]⁺ and [(NHC)₂SiCl₃]⁺ with tetrachloroborate as counterion. This is in contrast to previous reactions, in which NHC→SiCl₄ served as a transfer reagent for the NHC ligand. The addition of BF₃ ? OEt₂, on the other hand, gave NHC→BF₃ as the product of NHC transfer. In addition, the highly Lewis acidic bis(pentafluoroethyl)silane (C₂F₅)₂SiCl₂ was treated with NHC→SiCl₄. In acetonitrile, the cationic silicon(IV) complexes [(NHC)SiCl₃]⁺ and [(NHC)₂SiCl₃]⁺ were detected with [(C₂F₅)SiCl₃]^? as counterion. A similar result was already reported for the reaction of NHC→SiCl₄ with (C₂F₅)₂SiH₂, which gave [(NHC)₂SiCl₂H][(C₂F₅)SiCl₃]. If the reaction medium was changed to dichloromethane, the products of carbene transfer, NHC→Si(C₂F₅)₂Cl₂ and NHC→Si(C₂F₅)₂ClH, respectively, were obtained instead. The formation of the latter species is a result of chloride/hydride metathesis. These compounds may serve as valuable precursors for electron‐poor silylenes. Furthermore, the reactivity of NHC→SiCl₄ towards phosphines is discussed. The carbene complex NHC→PCl₃ shows similar reactivity to NHC→SiCl₄, and may even serve as a carbene‐transfer reagent as well.     

Inside Back Cover

A copper‐catalyzed aerobic oxidative ring expansion reaction of isatins with 1,2,3,4‐tetrahydroisoquinoline for the synthesis of tetracyclic quinazolinones has been developed. The capacity of the resultant 5H‐isoquinolino[1,2‐b]quinazolin‐8(6H)‐one for a range of palladium‐catalyzed directing C—H activation has been further demonstrated, thus giving a broader access to diverse tetracyclic quinazolinones. More details are discussed in the article by Xiao and Deng et al. on page 87—92.

     

Boosting Low‐Valent Aluminum(I) Reactivity with a Potassium Reagent

The reagent RK [R=CH(SiMe₃)₂ or N(SiMe₃)₂] was expected to react with the low‐valent (^DIPPBDI)Al (^DIPPBDI=HC[C(Me)N(DIPP)]₂, DIPP=2,6‐iPr‐phenyl) to give [(^DIPPBDI)AlR]^?K⁺. However, deprotonation of the Me group in the ligand backbone was observed and [H₂C=C(N‐DIPP)?C(H)=C(Me)?N?DIPP]Al^?K⁺ ( 1 ) crystallized as a bright‐yellow product (73 %). Like most anionic Al^I complexes, 1 forms a dimer in which formally negatively charged Al centers are bridged by K⁺ ions, showing strong K⁺???DIPP interactions. The rather short Al–K bonds [3.499(1)–3.588(1) Å] indicate tight bonding of the dimer. According to DOSY NMR analysis, 1 is dimeric in C₆H₆ and monomeric in THF, but slowly reacts with both solvents. In reaction with C₆H₆, two C?H bond activations are observed and a product with a para‐phenylene moiety was exclusively isolated. DFT calculations confirm that the Al center in 1 is more reactive than that in (^DIPPBDI)Al. Calculations show that both Al^I and K⁺ work in concert and determines the reactivity of 1 .