2,6-di-ferf-butylpyridine

The reaction of 2,6-di-ferf-butylpyridine with S03 at elevated temperatures gives (43) in addition to the 3-sulfonic acid.147... 

Me3SiCH2CH20CH2Cl, 2,6-di-ferf-butylpyridine, 48h, 56% yield. Other bases resulted in much lower selectivity and the formation of considerable bis-SEM ethers. ... 

The reported6 synthesis of the dodecamethylcarba-c/r o-dodecaborate(—) anion (CBnMe -) involved the use of the expensive sterically hindered base, 2,6-di-ferf-butylpyridine, in the second step. An optimized second step reported here utilizes calcium hydride as the only base. The overall procedure starting with CBnH12 provides a 84% yield of 99% pure Cs[CBnMe12]. Procedures for the conversion of the cesium salt to [Me NHCBiiMen] and Li CBj iMe ] are also described. Oxidation of the cesium salt to CBnMei2" is straightforward and proceeds in 76% isolated yield. 

Lanthanoids As mentioned in several cases above, some lanthanoid triflates displayed more or less catalytic activity for alkenol cyclizations. In one optimized case, several alkenol cyclizations were performed with Ln(OTf)3, Sm(OTf)3, and Yb(OTf)3 as catalysts (1 mol%) at 120°C in an ionic liquid as solvent (W-ethyl-W-methyl-imidazolium triflate) [73]. Addition of 2,6-di-ferf-butylpyridine blocked the activity of Yb(OTf)3 nevertheless, the authors argue that triflic acid, even though it catalyzed the reaction in a blind test, could not have been the hidden active catalyst, because triflic acid was not found by NMR spectroscopy in a vacuum transfer of volatiles from the reaction solution. 

Similarly, Karge et al. [398] employed pyridine and 2,6-di-tert-butylpyridine to differentiate between internal and external acid sites of zeolite crystallites. In this respect, another possibility is the use of lutidine [139] or quinoline. The latter probe was employed by Corma et al. [693] for the determination of external Bronsted and Lewis acid sites of H, Na-Y and Al, Na-Y zeolites (cf. also [694,695]). For a characterization of the external Bronsted and Lewis acidity of ZSM-5 samples, Keskinen et al. [696] utilized as sufficiently bulky bases trimethylsi-lyldiethylamine and, like Karge et al. [398], 2,6-di-ferf-butylpyridine. For the discrimination of external from internal acid sites of shape-selective H-ZSM-5 catalysts,Take et al. [135] utilized pyridine andabulkytrialkylamine (e.g.,Et3N, n-Pr3N and n-Bu3N) as a pair of probes, with the former indicating the total amount of acid sites. For quantitative evaluation they determined the extinction... 

Direct and site-selective C2-arylation of indole nucleus is more challenging than the corresponding Nl-arylation. Nonetheless, Gaunt s group achieved such a feat for N-acylindoles with aryliodonium salts using Cu(OTf)2 as the catalyst [215]. The mild reaction conditions tolerate a variety of functional groups (dtbpy = 2,6-di-ferf-butylpyridine). 

Di-ferf-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-f-butylpyridine can be alkylated under high pressure with Me0S02p to give >90% of the methylation product when water is carefully excluded. ... 

Feringa and coworkers reported a copper-catalyzed O-arylation of dialkyl phosphonates and phosphoramidates with diaryliodonium triflates and 2,6-di-ferf-butylpyridine (DTBP), giving easy access to mixed alkyl aryl phosphonates via elimination of one of the alkyl groups as the alkyl triflate prior to arylation (Scheme 10a) [133]. Aryl(mesityl)iodonium salts reacted in a chemoselective way. Copper-catalyzed arylations of hydroxamic acids [134] and carboxylic acids [135] have also been reported, the latter utilizing thiophosphoramides as cooperative catalysts to allow arylation at room temperature. Onomura s group discovered a Cu-catalyzed monoarylation of vicinal diols in toluene at 100 °C. Only traces of product were obtained with alcohols lacking the vicinal hydroxyl group [136]. 

A mixture of ethylene glycol, ethylene glycol ditosylate, and 2,6-di-rerr-butyl-pyridine stirred and heated to 180° with distillation of the volatiles -> dioxane. Y 70%. - Similarly trans-2,3-trans-5,6-diox2inQ-d. Y 65%. - Hindered bases, such as 2,6 di-ferf-butylpyridine, act as normal bases toward free protons, but do not act as nucleophiles. F. R. Jensen and R. A. Neese, J. Org. Chem. 37, 3037 (1972). 

---