Tert-Butyl pyridine

It was found that PhSOTf is superior to MeSOTf in terms of both yield and stereoselectivity of sialylation, especially when applied in combination with the hindered base 2,6-di(tert-butyl)-pyridine (DTBP) at low temperatures (—70 °C) [410]. Promoter was generated by the reaction of phenylsulfenyl chloride (PhSCl)... 

The sterically hindered base 2,6-bis(tert-butyl)pyridine does not inhibit cyclization triaryl-amine retards this reaction photosensibilized one-electron oxidation of a diene leads to the same products, which are formed in the presence of ammoniumyl salt. As shown, in majority of cases, only the cation-radical chain mechanism of the diene-diene cyclization is feasible (Bauld et al. 1987). Meanwhile, cyclodimerizations of 2,4-dimethylpenta-l,3-diene (Gassman and Singleton 1984) and l,4-dimethylcyclohexa-l,3- or -1,4-diene (Davies et al. 1985) proceed through both mechanisms. 

Fig. 14. Photoetection spectraof 2.4.6-tti-tert-butyl-pyridine S3 and 2.4.6-tri-tert-butyF -phosphorin 24...

Mach investigated hydrogen peroxide oxidation of 2.4.6-tri-tert-butyl-X -phos-phorin 24 in analogy to pyridine oxidation to pyridine-N-oxide. Whereas 2.4.6-tri-tert-butyl-pyridine could be recovered unchanged, 2.4.6-tri-tert-butyl-X -phos-phorin under the same conditions is irranediately oxidized to the 2-hydro-phos-phinic acid m.p. 203 °C (transformation at 170 °C) 86 (CH3 = H) which, accord-... 

Scheme 11. The thioglycoside linkage in 50 was activated to yield methyl glycoside 51 (DTBP, 2,6-di-tert-butyl-pyridine).

DPPN = 2,2-diphenylpropionitrile py = pyridine 2,6-lut = 2,6-dimethylpyridine, 2,6-lutidine 2,6,ditbpy = 2,6, di-tert-butyl-pyridine MA = methylamine DMA = dimethyl amine TMA = trimethylamine pX, mX, oX = para-, meta- and ortho-xylene. 

Figure 9. Dielectric strengths ASaCmd Aspof the mixture of 16 wt.% tert-butyl-pyridine (TBP) in tristyrene. Full symbols are for Ae of the a-relaxation (right axis) and open symbols for Asp of the JG f-re taxation (left axis). Dotted lines are linear fits of ASp below and above Tg. Dashed vertical line indicates T=211.5 K [where logjQ(zJs) 3] and is near the temperature at which occurs the crossover of temperature dependence of Asp with an elbow-shape.

Rate constants for the reaction of substituted pyridines with the 4-methoxystyrene radical cations have also been measured (Table 6). The bulky 2,6-di-tert-butyl pyridine reacts with the two methyl-substituted radical cations with rate constants of approximately 10 M s , but is substantially less reactive towards 4-methoxystyrene. This reaction has been attributed to deprotonation since electron transfer would be endergonic by -0.7 V and since the effects of methyl substitution at the P-carbon are opposite to those observed for other nucleophilic additions. 2,6-Dimethylpyridine also reacts with the two methyl-substituted radical cations with rate constants of 10 M s, but is approximately I order of magnitude more reactive towards the 4-methoxystyrene radical cation. The latter reaction must be nucleophilic addition since this radical cation cannot undergo deprotonalion. Product studies have confirmed that the reaction of 2,6-dimethylpyridine with the p-methyl-4-methoxystyrene radical cation is deprotonation. The major product of irradiation of a mixture of 1,4-dicyanobenzene, 4-methoxystyrene, and 2,6-dimethylpyridine is the rearranged tautomer, 3-(4-methoxyphenyljpropene, formed by a deprotonation, reduction, protonation sequence as shown in Eq. 19. By contrast to these... 

Figure 15.8. ORTEP drawing of the osmium tetraoxide adduct C6o(Os04) (4-tert-butyl pyridine)2.P l...

Corma, A., Forn s, V., Forni, L., Marquez, R, Martinez-Triguero, J., and Moscotti, D. 2,6-di-tert-butyl-pyridine as a probe molecule to measure external acidity of zeolites. J. Catal 1998,179, 451 58. 

A pyridinyl-functionalized ionic liquid, iV-butyl-]V -(4-pyridyIhept-yl)imidazolium bromide, cf. Figure 2.38, has been S5mthesized and applied as an additive for dye-sensitized solar cells (129). In comparison to a volatile organic additive, 4-tert-butyl pyridine, the bromine-containing compound can be used at a very low concentration for high overall power conversion efficiency cells, which shows an overall power conversion efficiency of 5.67% under the simulated air... 

Figure 2.40 Diethyl oxalate and 4-tert-Butyl pyridine.

Living carbocationic polymerization (LCCP) (Faust and Kennedy, 1987 Ivan and Kennedy, 1990 Joseph, 1999) relies on complex ion equilibria, which are normally maintained in the absence of polar solvents and monomers. Only specific polar additives (such as di-tert. butyl pyridine, or N,N-dimethyl acetamide) are compatible with a LCCP, so that the direct copolymerization of monomer containing H bonds is not possible. In the same manner, endquenching reactions with quenchers containing H bonds is not possible, as often only chlorine-telechelic polymers would result. 

Fig. 3. Synthesis of a 3 5 -methylene-bridged dithynudine. (i) CH3SCH2CI, NaH, THF (80% yield) (8) (11) CH3SCH3, benzoyl peroxide, 2,6-lutidine (75% yield) (10) (iii) NBS, 2,6-di-tert-butyl pyridine in CH2CI2, R = dimethylthexylsilyl (45% yield) (8) (iv) IDCT, R = C(0)CH20CH3 (yields only traces of dimer) (10).

Scheme 6.10 Synthesis of triflate-initiators from the corresponding alcohols by reaction with triflic anhydride in the presence of 2,6-di-tert-butyl pyridine as proton trap.

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