The base-promoted isomerization of benzyl oxiranyl ethers was investigated. In particular it was shown that the reaction may proceed toward two main regioisomeric products: a benzyl vinyl ether or a 2-aryl-3-(hydroxyalkyl)oxetane, depending on subtle variations in the substitution on the phenyl ring. Disubstituted oxetanes were obtained in a stereoselective manner, thus providing a good entry to this class of synthetically useful compounds.
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http://dx.doi.org/10.1021/jo960226d | DOI Listing |
J Am Chem Soc
November 2024
Frontiers Science Center for Transformative Molecules, School of Chemistry and Chemical Engineering, Zhangjiang Institute for Advanced Study, Shanghai Jiao Tong University, Shanghai 200240, China.
Nucleoside analogues have seen significant advancements in treating viral infections and cancer through ProTide technology, leading to a series of FDA-approved drugs such as sofosbuvir, tenofovir alafenamide, and remdesivir. The stereochemical configuration at the phosphorus center of ProTides significantly influences their pharmacological properties, necessitating efficient stereoselective synthesis. Traditional methods using chiral auxiliaries or nonracemic phosphorylating agents are labor-intensive and inefficient, while recent organocatalytic approaches, despite their promise, still face limitations.
View Article and Find Full Text PDFChem Commun (Camb)
April 2024
Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi'an 710062, China.
Ru-catalyzed asymmetric hydrogenation of α-substituted α,β-unsaturated ketones has been developed for the enantioselective synthesis of chiral α-substituted secondary alcohols with high diastereo- and enantioselectivities (up to >99 : 1 dr, 98% ee). Mechanistic experiments suggest that the reaction proceeds a Ru-catalyzed asymmetric hydrogenation of the CO bond in concert with a base-promoted allylic alcohol isomerization, and the final stereoselectivities were controlled by a DKR process during the asymmetric hydrogenation of the ketone intermediate.
View Article and Find Full Text PDFCarbohydr Res
December 2023
N. D. Zelinsky Institute of Organic Chemistry of the Russian Academy of Sciences, Leninsky Prosp. 47, 119991, Moscow, Russian Federation. Electronic address:
Base-promoted (MeONa in MeOH or imidazole in DMF) isomerization of a series of 3,4,6-tri-O-benzyl-d-gluco- and d-mannopyranose derivatives with triisopropylsilyl (TIPS) substituents was studied. The presence of a bulky TIPS group at O-1 or O-2 was shown to be favorable for the isomerization of benzyl protected d-gluco- and d-mannopyranose derivatives to d-fructofuranose derivatives, in which the bulky silyl group occupies less sterically hindered primary position. The highest yield (33%) of the fructofuranose derivative was achieved when 3,4,6-tri-O-benzyl-2-O-triisopropylsilyl-d-mannopyranose was treated with MeONa in MeON at 50 °C.
View Article and Find Full Text PDFMolecules
August 2023
School of Chemistry and Chemical Engineering, Nantong University, Nantong 226019, China.
Org Biomol Chem
September 2023
Università di Parma, Dipartimento di Scienze Chimiche, della Vita e della Sostenibilità Ambientale, Parco Area delle Scienze 17/A, 43124 Parma, Italy.
We report a BuOK-promoted synthesis of 1,3-dihydro-2-pyrrol-2-one and 4-methylenepyrrolidin-2-one systems like intramolecular cyclization. The method features extremely short reaction times (5 min) and mild reaction conditions (rt), enabling the trapping of a propargyl unit by an amide enolate. An intriguing anionic chain mechanism is at work, which can trigger the isomerization of an -alkene giving access to the otherwise elusive -product.
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