Acetophenone, acid-catalyzed electron

The ke[ values of photoinduced electron transfer reactions from [Ru(bpy)3]2 + to various nitrobenzene derivatives in the presence of 2.0 mol dm-3 HC104 are listed in Table 1, where the substituent effect is rather small irrespective of electron-withdrawing or donating substituents. A similar insensitivity to the substituent effect is also observed in the acid-catalyzed photoinduced electron transfer from [Ru(bpy)3]2+ to acetophenone derivatives [46,47]. The stronger the electron acceptor ability is, the weaker is the protonation ability, and vice versa. Thus, the reactivity of substrates in the acid-catalyzed electron transfer may be determined by two reverse effects, i.e., the proton and electron acceptor abilities, and they are largely canceled out. Such an insensitive substituent effect shows a sharp contrast with the substituent effect on the acid-catalyzed hydride transfer reactions from Et3SiH to carbonyl compounds, in which the reactivity of substrates is determined mainly by the protonation ability rather than the electron acceptor ability. 

Figure 4A. Dependence of kcl on [HC104] for the acid-catalyzed photoinduced electron transfer from [Ru(bpy)3]2 + to acetophenone in the presence of HC104 in MeCN at 298 K [40].

Fig. 41 Perchloric acid catalyzed ET from photoexcited Ru(bpy) to acetophenone derivatives. A r d corresponds to the positive shift in the one-electron reduction potential observed in the presence of perchloric acid relative to the one-electron reduction potential observed in the absence of perchloric acid...

Various substituted phenols were selectively synthesized by a one-pot reaction through the NHPI-catalyzed aerobic oxidation of l,l -diarylethanes to hydroperoxides followed by treatment with dilute sulfuric acid [75]. For example, the oxidation of l-(4-methoxyphenyl)-l-phenylethane was performed under O2 (1 atm) in the presence of AIBN (3 mol%) and NHPI (10mol%) in MeCN (3mL) at 75 °C for 15 h, and treatment with sulfuric add afforded 4-methoxyphenol and acetophenone in 61% yield (97% selectivity) at 63% conversion (Eq. (6.17)). In this reaction, the degradation of hydroperoxides was selectively induced to give more electron-rich phenols in high selectivity (Scheme 6.6). 

W ang and coworkers have reported the Pd-catalyzed coupling reaction of arylboronic acids with diazo compotmds [84], In 2010, oxidative Pd-catalyzed coupling of Al-tosylhydrazones with arylboronic acids was reported by the same group (Fig. 24) [103]. Under the optimized conditions the reaction of a series of arylboronic acids with substituted acetophenone IV-tosyUiydrazmies proceeds well to afford substimted olefins in acceptable yields. Experimental results indicate that no significant electronic effect and ZIE selectivity have been observed in the reacticMi. 

Adolfsson et al. have used related amino acid-derived mOTio-l,4-disubstituted-1,2,3-triazole containing tridentate chelators, 86, as ligands in ATH reactions (Fig. 19) [190]. The authors screened a family of ligands with different steric and electronic properties in the Rh(I)-catalyzed ATH of acetophenone to 1-phenyethanol and showed that the use of these click catalysts led to good conversion (62-79%) and high ee (71-93%). 

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