699-73-0Relevant articles and documents
Silver-Promoted Radical Ring-Opening/Pyridylation of Cyclobutanols with N-Methoxypyridinium Salts
Chen, Yu,Zhang, Guang-Yi,Guo, Chan,Lan, Ping,Banwell, Martin G.,He, Yu-Tao
supporting information, (2022/03/03)
The silver-promoted reaction of tertiary cyclobutanols with N-methoxypyridinium salts enables the efficient synthesis of a range of C2-substituted pyridines. The overall process likely occurs by ring-opening (via β-scission) of the cyclobutoxy radical to generate the corresponding γ-keto alkyl radical that itself adds to the pyridinium salt. A wide range of tertiary cyclobutanols and N-methoxypyridinium salts are compatible with the reaction conditions.
Highly Enantioselective, Hydrogen-Bond-Donor Catalyzed Additions to Oxetanes
Strassfeld, Daniel A.,Wickens, Zachary K.,Picazo, Elias,Jacobsen, Eric N.
supporting information, p. 9175 - 9180 (2020/07/13)
A precisely designed chiral squaramide derivative is shown to promote the highly enantioselective addition of trimethylsilyl bromide (TMSBr) to a broad variety of 3-substituted and 3,3-disubstituted oxetanes. The reaction provides direct and general access to synthetically valuable 1,3-bromohydrin building blocks from easily accessed achiral precursors. The products are readily elaborated both by nucleophilic substitution and through transition-metal-catalyzed cross-coupling reactions. The enantioselective catalytic oxetane ring opening was employed as part of a three-step, gram-scale synthesis of pretomanid, a recently approved medication for the treatment of multidrug-resistant tuberculosis. Heavy-atom kinetic isotope effect (KIE) studies are consistent with enantiodetermining delivery of bromide from the H-bond-donor (HBD) catalyst to the activated oxetane. While the nucleophilicity of the bromide ion is expected to be attenuated by association to the HBD, overall rate acceleration is achieved by enhancement of Lewis acidity of the TMSBr reagent through anion abstraction.
Catalytic Friedel-Crafts Reactions on Saturated Heterocycles and Small Rings for sp3-sp2 Coupling of Medicinally Relevant Fragments
Croft, Rosemary A.,Dubois, Maryne A. J.,Boddy, Alexander J.,Denis, Camille,Lazaridou, Anna,Voisin-Chiret, Anne Sophie,Bureau, Ronan,Choi, Chulho,Mousseau, James J.,Bull, James A.
supporting information, p. 5385 - 5395 (2019/06/24)
gem-Diarylheterocycles display a wide range of biological activity. Here we present a systematic study into the formation of 4- to 6-membered O- and N-heterocycles and cyclobutanes bearing the diaryl motif through a catalytic Friedel–Crafts reaction from the corresponding benzylic alcohols. 3,3-Diaryltetrahydrofurans, 4,4-diaryltetrahydropyrans, 3,3-diarylpyrrolidines, 4,4-diaryl-piperidines, as well as diarylcyclobutanes are examined, with results for 3,3-diaryloxetanes and 3,3-diarylazetidines presented for comparison. Three catalytic systems are investigated for each substrate [Ca(II), Li(I) and Fe(III)], across preinstalled aromatic groups of differing electronic character. In most cases examined, the diaryl product is obtained directly from the alcohol with good yields using the most appropriate catalyst system. In the absence of a nucleophile, the olefins from the 5- and 6-membered substrates by elimination of water are obtained under the same reaction conditions.
Catalytic enantioselective intermolecular desymmetrization of 3-substituted oxetanes
Wang, Zhaobin,Chen, Zhilong,Sun, Jianwei
supporting information, p. 6685 - 6688 (2013/07/26)
Wring it out: The title reaction proceeds in the presence of chiral Bronsted acid catalysts. This efficient ring-opening process features low catalyst loading, mild reaction conditions, broad functional group compatibility, high enantioselectivity, and the capability to generate chiral quaternary centers. The highly functionalized desymmetrization products are versatile chiral building blocks in organic synthesis. Copyright
Surface photochemistry: the photolysis of α-methoxy acetophenones on silica gel
Mayo, Paul de,Ramnath, N.
, p. 1293 - 1296 (2007/10/02)
The photolysis of α-methoxy acetophenones 1a-1e adsorbed on silica gel show a significant deviation from the course of reaction in methanol.The results are discussed in terms of conformational control and restricted movement of the radical through adsorption on silica gel.Factors affecting the efficiency of modification of photochemical reactivity on silica gel surface have been examined.
Syntheses and Reactions of 3-Phenyloxete and the Parent Unsubstituted Oxete
Friedrich, Louis E.,Lam, Patrick Yuk-Sun
, p. 306 - 311 (2007/10/02)
The elimination of p-toluenesulfonic acid and o-nitrophenylselenilic acid from substituted oxetanes gives 3-phenyloxete (6) and oxete (9), respectively. 3-Phenyloxete (6) undergoes the expected chemistry as well as a facile addition of triplet oxygen to g