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Pivalic acid, oxidative coupling

Piperazine, N-alkylation with benzyl chloride, 42, 19 Piperazine, 1-benzyl-, 42,19 Piperidine, addition to ethylene, 43, 45 as catalyst for Claisen-Schmidt condensation, 41, 40 Piperidine, 1-ethyl-, 43, 45 Piperidine, 1-(2-naphthyl)-, 40,74 Pivalic acid, oxidative coupling to a,a,-a, a -tetramethyladipic add, 40, 92... [Pg.120]

Piperidine as catalyst for Claisen-Schmidt condensation, 41, 40 Pivalic acid, oxidative coupling to a,a,-a, a -tetramethyladipic acid, 40, 92... [Pg.59]

O/t/20-arylation of benzoic acids is often preferable to ortho-arylation of benzamides if conversion of the amide moiety to other functional groups is desired. However, only a few reports have dealt with the orf/io-functionalization of free benzoic acids due to challenges that involve such transformations. The reactions can be complicated by decarboxylation of the product and the starting material. Despite those difficulties, several methods for direct o/t/io-arylation of benzoic acids have been developed. Yu has shown that arylboronates are effective in arylation of benzoic acids under palladium catalysis [59], The reactions require the presence of palladium acetate catalyst, silver carbonate oxidant, and benzoquinone. Even more interestingly, the procedure is applicable to the arylation of unactivated sp3 C-H bonds in tertiary carboxylic acids such as pivalic acid (Scheme 13) if aryl iodide coupling partner is used. Aryl trifluoroborates can also be used [60],... [Pg.68]

The second example of the hypoiodite-catalyzed C-C coupling reaction is represented by the C3-selective formylation of indoles 149 to products 150 by using A-methylaniline as a formylating reagent in the presence of catalytic B114NI and tert-butyl peroxybenzoate as the terminal oxidant (Scheme 4.76) [118]. Pivalic acid is... [Pg.374]

The C-2 selective oxidative C-H coupling of unactivated pyridines with heterocycles was achieved in the presence of Pd(OAc)2, phenanthroline as the ligand, a silver oxidant, and pivalic acid (eq 145). Moderate to good yields were obtained when heteroarenes, such as thiophenes, indoles, furans, indazoles, or xanthines, were coupled to p3uidine (or p3razine, quinoline, pyrimidine). Virtually no homo-coupling or other regioselective (C-3 or C-4) products were observed in the reaction. [Pg.479]

An intramolecular cross-dehydrogenative coupling of 1,2,3-triazoles with arenes was reported in the presence of Cu(OAc)2 as the oxidant and pivalic acid as the additive (eq 172). ... [Pg.484]

Low yields were obtained in the absence of pivalic acid however, employing greater than 30% pivalic acid did not further improve yields or reactivity. Substrates that performed well included C3-substituted benzothiophenes, C2-substituted thiophenes, pyrroles, imidazole, triazole, imidazopyridine, thiazole, and oxazoles, which could be efficiently arylated with aryl bromides. Unfortunately, benzofuran produced low yields (29% with 2-bromotoluene), and furans encountered issues with diarylation, which could be minimized by using more sterically hindered aryl bromides. Arylation of indolizines could be achieved, albeit electron-deficient aryl bromides required longer reaction times (16-24 h). Heterocyclic aryl bromides, such as 3-bromopyridine, could also be employed with thiazole. Problematic aryl halides included cyano, nitro, acetyl, pyridyl functionalities, and N-heterocyclic V-oxides. Other coupling partners, such as aryl tri-flates and aryl chlorides, performed poorly under the reaction conditions. Unsuitable heterocycles included unprotected imidazoles, 2-aminothiazole, isoxazole, benzothiazole, and benzoxa-zole, which failed to produce arylated products. [Pg.537]

Pyridine could be selectively C2-heteroarylated with various azole coupling partners using silver(I) acetate. Other oxidants, such as benzoquinone (BQ), O2, and Cu(OAc)2, were ineffective. When 1.0 equiv of pivalic acid was added, the yields were dramati-... [Pg.540]

Silver(I) carbonate functioned as an oxidant in combination with TBAI to provide optimal yields. Pivalic acid was superior to pyridine as an additive. Thiazole, pyrazole, thiophene, and pyrrole substrates could be cross-coupled however, heteroarenes bearing electron-donating substituents afforded better yields compared with electron-withdrawing groups. The reactions proceeded in high regioselectivity at the C2/C5 position. [Pg.541]

To date, only one report has referred to the direct allqmylation of indoles under aerobic conditions. In 2010, Li and co-workers described a palladium-catalyzed oxidative coupling of 1,3-dimethylindoles with phenylacetylenes." Using a buffer system composed of 20 mol% cesium carbonate and 2 equiv. pivalic acid at 80 °C, the desired cross-coupling products were obtained in moderate-to-good yields (Scheme 9.21). [Pg.208]


See other pages where Pivalic acid, oxidative coupling is mentioned: [Pg.48]    [Pg.74]    [Pg.189]    [Pg.238]    [Pg.120]    [Pg.539]    [Pg.557]    [Pg.602]    [Pg.20]    [Pg.206]    [Pg.433]    [Pg.41]    [Pg.521]    [Pg.128]   


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