Construction of C–O bond via cross-dehydrogenative coupling of sp [ ] C–H bond with phenols catalyzed by copper porphyrin

A novel quinoline-based NNN-pincer Cu(ii) complex as a superior catalyst for oxidative esterification of allylic C(sp3)–H bonds

“…Thus, in the reaction pathway, the generated allylic radical, in the presence of the catalyst, attaches itself to the O atom of the acid counterpart, yielding the ester. On the basis of the experimental results obtained above and the reported literature, 41 a plausible reaction mechanism for the allylic esterification of aromatic esters and cyclohexene is shown in Scheme 3. First, TBHP is converted to its tert -butoxy radical and hydroxyl radical by homolytic bond cleavage and then the tert -butoxy radical, generated through hydrogen atom transfer (HAT), is inserted into catalyst 1 , changing the oxidation state of the metal centre from +2 to +3.…”

Copper porphyrin‐catalyzed C(sp2)—O bond construction via coupling phenols with formamides

“…Other M-TECP catalysts (M = Fe, Ni, Pd, Co, Ag, Mn, Zn) were also investigated but all of that were inactive for this reaction (Table 1, entries [12][13][14][15][16][17][18]. Meanwhile, tetrakis(perfluorophenyl)porphyrinato)copper(II) (CuF 20 TPP) (Figure 1) and copper acetate were tested but both of them gave poor yields (Table 1, entries [19][20], indicating the electron-deficient ligand superiority of CuTECP in this reaction. Besides, the desired product could not be obtained in the absence of oxidant or catalyst (Table 1, entries [21][22].…”

“…All metalloporphyrins were synthesized based on our reported procedure and spectral data were found identical to previous reports. [17] 1 H, 13 C, and 19 F NMR spectra were obtained on Bruker Avance 400 M NMR and Bruker Ascend 500 M spectrometers. The high-resolution mass (HR-MS) spectra were obtained on Agilent 6210 ESI mass spectrometer.…”

“…13 C NMR (101 MHz, CDCl 3 ) δ 161.2, 158.8, 155.0, 147.5, 123.3, 123.2, 116.0, 115.8, 77.5, 77.2, 76.8, 36.9, 36.5. 19 F NMR (376 MHz, CDCl 3 ) δ −118.12, −118.13, −118.15, −118.15.…”

“…[ 18 ] Moreover, we have also achieved the oxidative coupling of cyclic ethers and phenols accessing to C(sp 3 )—O bonds by using copper TECP as catalyst (Scheme 1, a). [ 19 ] To the best of our knowledge, the example about metalloporphyrin‐catalyzed formation of C(sp 2 )—O via CDC reaction has not been reported. To extend our work in the metalloporphyrin‐catalyzed CDC reaction, we herein wish to report the coupling of phenols and formamides to construct C(sp 2 )—O bond by using metal TECP complexes (M‐TECP) (Figure 1).…”