Synthese von 1,2,3‐trisubstituierten Indanen durch diastereoselektive Palladium‐katalysierte Oxyarylierung von Indenen mit Arylboronsäuren und Nitroxiden

Direct CH Bond Arylation of Indoles with Aryl Boronic Acids Catalyzed by Palladium Nanoparticles Encapsulated in Mesoporous Metal–Organic Framework

“…The presence of a base is known to be beneficial in the transmetalation of aryl boronic acids towards homocoupling reaction products. However, the presence of an acid could reduce the rate of transmetalation and facilitate the electrophilic attack 27–29. The MOF material MIL‐101 as a support is stable in the presence of an acid (Figure 2).…”

“…N ‐Methylindole can be activated effectively by only 0.5 mol % Pd catalyst, and a high isolated yield was obtained (85 %; Table 1, entry 20). In contrast, the higher catalyst loadings (up to 5 %) are generally required in the homogeneous catalysis system 27–29. In addition, 1 equiv.…”

“…Studer and co‐workers presented Pd‐catalyzed chemodivergent chemical modifications of various indoles with arylboronic acids and 2,2,6,6‐tetramethylpiperidine N ‐oxyradical (TEMPO) as a mild oxidant 28. 29 Depending on the substituent on the indole N atom, either direct C2 arylation (R=H, Me) or highly diastereoselective arylcarboaminoxylation (R=Ac, Bz, Boc) occurs. However, unfortunately, the expensive Pd catalysts in homogeneous forms are difficult to separate from the products and cannot be recovered, which affects cost and causes the environmental pollution from heavy metallic ions.…”

Microwave‐Promoted Palladium‐Catalysed Oxyarylation of Dihydronaphthalene and Chromenes by o‐Iodophenols and Its Acetates

“…For instance, a Pd‐catalysed oxyarylation of phenylpropenes by diazonium salts, generated in situ from o ‐aminophenols, has been used to prepare trans ‐2,3‐disubstituted dihydrobenzofurans (DHBs), a structural motif present in naturally occurring 8,5′‐neolignans 6. Also, a highly diastereoselective Pd‐catalysed oxyarylation of indenes with arylboronic acids and nitroxides has been recently employed for the synthesis of 1,2,3‐trisubstituted indanes 7 . o ‐Iodophenol derivatives have been successfully used to achieve the Pd‐catalysed oxyarylation of olefins, a methodology that has allowed the synthesis of a wide variety of oxygen‐containing heterocycles 8.…”