591-35-5Relevant articles and documents
C-H nickellation of phenol-derived phosphinites: Regioselectivity and structures of cyclonickellated complexes
Mangin, Lo?c P.,Zargarian, Davit
, p. 16159 - 16170 (2017)
This report describes the results of a study on the ortho-C-H nickellation of the aryl phosphinites i-Pr2P(OAr) derived from the following four groups of substituted phenols: 3-R-C6H4OH (R = F (b), Me (c), MeO (d), Cl (e)); 3,5-R2-C6H3OH (R = F (f), Me (g), Cl (h), OMe (i)); 2-R-C6H4OH (R = Me (j), Ph(k)); and 2,6-R2-C6H3OH (R = Me (l), Ph (m)). No nickellation was observed with the phosphinites derived from the 3,5-disubstituted phenols g and h, and the 2,6-disubstituted phenols l and m; in all other cases nickellation occurred at an ortho-C-H to generate either the Br-bridged dimers [{κP,κC-(i-Pr)2POAr}Ni(μ-Br)]2 (1b-1f, 1j, and 1k) or the monomeric acetonitrile adduct {κP,κC-ArOP(i-Pr)2}Ni(Br)(NCMe) (1i-NCMe). Analysis of C-H nickellation regioselectivity with 3-R-C6H4OH pointed to the importance of substituent sterics, not electronics: nickellation occurred at the least hindered position either exclusively (for R = Me (c), MeO(d), and Cl (e)) or predominantly (for R = F (b); 6:1). This conclusion is also consistent with the observation that C-H nickellation is possible with the 3,5-disubstituted aryl phosphinites bearing F and OMe, but not with the more bulky substituents Me or Cl. For the 2-substituted aryl phosphinites, C-H nickellation occurs at the unsubstituted ortho-C-H and not on the R substituent, regardless of whether the alternative C-H moiety of the substituent is sp3 (R = Me (j)) or sp2 (R = Ph (k)). The system thus reveals a strong preference for formation of 5-membered metallacycles. Consistent with this reactivity, no nickellation occurs with (2,6-R2-C6H3O)P(i-Pr)2. Tests with the parent dimer derived from i-Pr2P(OPh) showed that conversion to the monomeric acetonitrile adduct is highly favored, going to completion with only a small excess of MeCN. All new cyclonickellated complexes reported in this study were fully characterized, including by single crystal X-ray diffraction studies. The solid state structures of the dimers 1b and 1d showed an unexpected feature: two halves of the dimers displayed non-coplanar conformations that place the two Ni(ii) centers at shortened distances from each other (2.94-3.16 ?). Geometry optimization studies using DFT have shown that such non-coplanar conformations stabilize the complex, implying that the "bending" observed in these complexes is not caused by packing forces. Indeed, it appears that the occurrence of coplanar conformations in the solid state structures of these dimers is a simple consequence of packing forces rather than an intrinsic property of the compound.
Reticular Synthesis of tbo Topology Covalent Organic Frameworks
Kang, Xing,Han, Xing,Yuan, Chen,Cheng, Cheng,Liu, Yan,Cui, Yong
supporting information, p. 16346 - 16356 (2020/10/26)
The metal-organic framework (MOF) HKUST-1 with a tbo topology serves as an archetypal tunable and isoreticular framework platform for targeting desired applications, but the design and synthesis of tbo-covalent organic frameworks (COFs) remains a formidable challenge. Here we demonstrate the successful use of reticular chemistry as an appropriate strategy for the design and deliberate construction of COFs with a tbo topology. The judicious selection of the perquisite planar building blocks, 4-connected square tetramine of porphyrin and 3-connected trigonal trialdehydes of triphenylamine, allows the condensation of two tbo-COFs, the first examples of COFs with a tbo topology. The resulting COFs both crystallize in the cubic Pm3ˉ space group and adopt a non-interpenetrated open framework, in which each tritopic linker connects to three square units forming a truncated Td-octahedron and occupies the alternating triangular faces of the truncated octahedron. Owing to the presence of two different types of photoredox-active moieties, the two COFs can be efficient heterogeneous photocatalysts for the oxidative hydroxylation of arylboronic acids and the reductive defluoroalkylation of trifluoromethyl aromatics with alkenes. The present finding will provide an impetus to examine the potential of tbo-COFs as a new platform for engineering multifunctional materials via expansion and functionalization of building blocks.
Oxidative hydroxylation of arylboronic acids to phenols catalyzed by copper nanoparticles ellagic acid composite
Affrose, Abdullah,Azath, Ismail Abulkalam,Dhakshinamoorthy, Amarajothi,Pitchumani, Kasi
, p. 500 - 505 (2014/12/10)
Copper nanoparticles (Cu NPs) were prepared by in situ reduction of CuSO4·5H2O using ellagic acid (EA) as the reducing agent as well as stabilizer and its catalytic activity is tested in the oxidative hydroxylation of phenylboronic acids to phenol without any added base or ligand. The synthesized Cu NPs-EA composite was characterized by UV-Vis., FT-IR, powder XRD and HRTEM analyses. The average particle size of Cu NPs is found to be in the range of 20-25 nm as evident from HRTEM and copper content is estimated to be 3.18 wt%. EA acts both as a reducing agent as well as a stabilizer for the in situ formation of Cu NPs. A small portion of Cu NPs is also found to undergo aerobic oxidation to give Cu2O NPs which does not take part in the reactions. A series of arylboronic acids are converted to the corresponding phenols in high yields at short reaction time under milder reaction conditions. It is also observed that Cu NPs-EA composite can be reused at least four times with a significant decrease in the yield.
