2.6- Di-r-butylpyridine

Similar ring openings have been achieved using trimethylsilyl triflate and 2,6-di-r-butylpyridine.155... 

Aminopyridine and l-methyl-2-pyridone are sulfonated under milder conditions (H2S04-S03, 140°C) in the 5-position. 2,6-Di-r-butylpyridine is converted into the 3-sulfonic acid under mild conditions (S02-S03, 0°C) because reaction of S03 at the nitrogen atom is prevented sterically thus, reaction occurs on the free base, under conditions where this is the majority species. 

Methylation of alcohols1 (6,406). The sensitive aldol product 1 was converted to the corresponding methyl ether in 83% yield by reaction with methyl triflate (15 equiv.) and 2,6-di-r-butylpyridine (30 equiv.) in CHC13 at 80° without retro-aldol cleavage or epimerization. 

The sterically hindered 4-methyl-2,6-di-r-butylpyridine (MDTBP) has been used to elucidate the mechanism of carbocationic polymerization (80MI3),... 

The electrochemical behavior of compound XI [80] is different as no catalytic effect is registered in the presence of bromide ions. Electrolysis under controlled-potential conditions in MeCN containing water and an excess of 2,6-di-r-butylpyridine provides the corresponding sulfoxides as a mixture of diastereomers in 60 and 25-30% yield, respectively. 

AgOTf, 2,6-di-r-butylpyridine 1° alkyl iodide, PhCH2Cl, H2C=CHCH2Br TL 35 8111 (1994)... 

Methylation of carbohydrates. Carbohydrates can be methylated in >80% yield by methyl triflate and a sterically hindered, weak base such as 2,6-di-r-butylpyridine and 2,6-di-f-butyl-4-methylpyridine. The method is useful for sugars that are sensitive to acids or bases. 

For the epoxidation of alkenes sensitive either to acids alone or to both acids and bases, the presence of 2,6-di-r-butylpyridine is advantageous. Liposomized MCPBA is useful for enantioselective epoxidation (ee 62-95%). ... 

Certain basic materials have been used to deactivate surface acidity. By modifying the surface acidity of HZSM-5 with 4-methylquinoline or hexamethyl-disilazane more linear products have been obtained in propene oligomerization, and, by modifying the surface acidity of HZSM-5 with 2,6-di-/ r/-butylpyridine,... 

To a solution of 610 mg iV-(/-butyloxycarbonyl)-lV-(methanesulfonyloxy)cyclopent-3-enylcarboxamide (2.0 mmol) in 10 mL CH3CN were added 238 mg benzyl alcohol (2.2 mmol), 382 mg 2,6-di-r-butylpyridine (2.0 mmol), and 72 mg zinc triflate (0.2 mmol). The mixture was heated with stirring at 85°C for 16 h and then cooled to room temperature. It was then diluted with 50 mL EtOAc, washed with water, 1 M H3PO4, and brine (50 mL each). The combined aqueous layers were back extracted with ethyl acetate (2 X 50 mL) the combined organic layers were dried over MgS04, filtered, and concentrated in vacuo. The residue was flash chromatographed (4 1, hexanes/EtOAc) to afford 352 mg iV-(benzyloxycarbonyl)cyclopent-3-enylamine as a colorless solid, in a yield of 81%, m.p. 50-52°C. 

Kennedy and coworkers investigated polymerizations initiated by Lewis acids-water in the presence of one such proton trap, 2,6-di-r-butylpyridine. The presence of this base markedly decreased conversion from almost 1(X)%, in some cases, to only a few percent. At the same time, there was a marked increase in the molecular weight and a narrowing of the molecular weight distribution of the products. This shows that the protonic reaction is by far the most in ortant mode of initiation. It also suggested to Kennedy and coworkers that not all the protonic initiations occur... 

A number of control reactions were carried out in order to assess the importance of the individual components of TBA3H2I. First, a model (Table I, entry 2) of the active catalyst comprising TBA4Fe(H20)PWn039, TBANO3 and a proton source (p-toluenesulfonic acid, pTsOH) in the same mole ratios to entry 1 was evaluated. The catalytic activity of this model system is similar to that of the active catalyst. Upon removal of the POM from the system, the catalytic activity is lower (entry 3). The addition of a proton-specific base, 2,6-di-r-butylpyridine, to the active catalyst, TBA3H2I, results in complete loss of activity (entry 4). Other NOx species (including, but not limited to, entries 5 and 6) show minimal activity. Thus, all components of the reactive system, POM, nitrate, and proton, are essential for optimal catalysis of eq 1. 

The mechanism of the oxidation of 2-mercapto-5-methyl-l,3,4-thiadiazole (McMT) to its disulfide dimer and its subsequent reduction was examined with a combined approach employing experimental data and digital simulation. To elucidate the influence of proton transfers on these redox processes, special attention was paid to the influence of various bases and proton donors on both the oxidation and reduction reactions. In particular, McMT oxidation is facilitated by a rapid bimolecular proton transfer from McMT to weak bases such as pyridine that produces McMT , the thiol-ate form, which is then oxidized. There is no such facilitation in the presence of the sterically hindered base 2,6-di-r-butylpyridine, suggesting that the facilitation occurs through the formation of a discrete hydrogen-bonded complex/ ... 

MID = 1-methylimidazole, DTBP = 2,6-di-r-butylpyridine, DMP dimethylpyridine, DTBMP = 2,6-di-r-butyl-4-methylpyridine. 

Di-t-butylpyridine does not react at normal pressure, and this or 2,6-di-f-butyl-4-methylpyridine (synthesis ), are often used in applications which require base (see below). Note that 2,6-di-r-butylpyridine can be alkylated under high pressure with Me0S02p to give >90% of the methylation product when water is carefully excluded. 

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