2-Butyl-pyridine

While asymmetric approaches are certainly important, other synthetically significant epoxidation protocols have also been reported. For example, buffered two-phase MCPBA systems are useful for epoxidations in which the alkenes and/or resultant epoxides are acid-sensitive. Bicarbonate works quite well for cinnamate derivatives (e.g., 55) <96SC2235> however, 2,6-di-t-butyl-pyridine was shown to give superior results in the case of certain allyl acetals (e.g., 57) <96SC2875>. 

JOC3172, 1996J(P2)2085>. Chemical electron transfer (CET) oxidation of these bicyclic housanes with tris(4-bromophenyl)aminium hexachloroantimonate performed at 0°C in the absence or presence of base (2,6-di-/-butyl-pyridine) leads to the formation of two olefinic products 369 and 370, which were isolable after flash chromatography on silica (Scheme 56) <1996JOC3172>. 

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)... 

Die Reaktion von 3-Butyl-pyridin mit Methylradikalen, by E. Hardegger and E. Nikles, Helv. Chim. Acta, 40 (1957) 2421-2427. 

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. 

Enamines or imines can form pyridines by cyclization to a nitrile group, as shown in the production of compound (48). Alternatively, the nitrogen atpm of the nitrile can be made more nucleophilic by attack on the carbon atom by an external nucleophile. Ammonia causes cyclization of the dienamines (53) (77JHC1077) and (54) (78JAP(K)786878l) in both cases, elimination of the amine introduces the extra double bond. Dimethylamine or piperidine cause cyclization of l-cyano-2,5,5-trimethylhex-l-en-3-yne to the f-butyl-pyridine (55). There are a few other examples of the synthesis of bicyclic compounds from... 

CN 1. N2H4 H20/Pd —C/C2HjOH 20 25° bis zum Verschwinden der Trubung dann fillrieren 2. N2H4 H20/Raney-Ni 7um Filtrat 50-55 bis zum Verschwinden der Trubung 3-Amino-2-( 4-amino-butyl) -pyridin 96 6... 

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-... 

PPME = protoporphyrin IX dimethylester, Melm = 1-methylimidazole, BuPy = butyl-pyridine, Py = pyridine, PSP = copolymer of styrene and 4-vinylpyridine (vinylpyridine content 23%, molecular weight 1.1 x 104). 

TiCl4 treatment and calcined at 450 C Soaking film in dye solution for a overnight ( butyl pyridine (TBP) treatment. 

A combination of trityl tetrafluoroborate or perchlorate with 2,4,6-tri(/err-butyl)-pyridine instead of pyridine enables an almost quantitative tritylation of the secondary hydroxyl group in l,2 5,6-di-0-isopropylidene-a-D-glucofuranose in 10 min at room temperature [321]. The more readily available 2,6-di(/m-butyl)-4-methylpyridine was used [322] in combination with trityl perchlorate for the selective tritylation of methyl 2,6-di-0-acetyl-a-D-galactopyranoside at the equatorial OH-3. Combination... 

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

Pyridylmethylphosphinates can be accessed, albeit in low isolated yield, by palladium-catalyzed cross-coupling of 2- and 3-pyridylmethyl chlorides with anilinium hypophosphites <2005T6315>. For example, 3-chloromethylpyr-idine hydrochloride reacts with anilinium hypophosphite in the presence of Pd(OAc>2, dppf, 1,4-diazabicy-clo[2.2.2]octane (DABCO), and (BuOTSi as esterification agent to give butyl (pyridine-3-ylmethyl)phosphinate 53 in 46% yield (Equation 37). This transformation proceeds in 24% yield when performed on 2-chloromethylpyridine. 

More interestingly, in the same report the authors observed that the quantum yield for the TCA-sensitized photooxygenation of 25 substantially increased by carrying out the reactions in the presence of catalytic amounts of acid (tri-fluoroacetic acid 10 2 10 3 M) or nucleophiles such as pyridine, 2-t-butyl-pyridine, 4-picoline [99]. 

A very interesting reaction of an epoxide with WC16 provides the trans-dichloride <07TL8388>. The reaction proved compatible with a number of functional groups including esters, sulfones, and even silyl ethers (with the addition of 2,6-di-t-butyl pyridine). Olefins and alcohols were converted to the chlorides. 

Osmylation of Ceo with OSO4, in the presence of 4-t-butyl-pyridine (L), yields the osmyl ester Ceo[Os04L2] (12), the first stmcturally characterized Ceo derivative. The OSO4 adds across a six-six ring junction, in a similar manner to the dioxolane derivative (9), and the two sp hybridized carbon atoms are moved away from the center of the cage center-to-C(sp ) distances, 3.80 A average center-to-C(sp ) distance. 

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