In this study, we describe the intramolecular Baeyer-Villiger oxidation of ketones to esters using N-oxide. 2-Nitro-N-alkyl-N-(2-oxo-2-phenylethyl)benzenesulfonamide compounds are known to undergo base-mediated C-arylation followed by N-N bond formation, producing unstable five-membered ring intermediates that spontaneously dehydrate to indazole oxides. We identified the reaction conditions under which the cyclic intermediate undergoes acid-mediated intramolecular Baeyer-Villiger oxidation of the ketone in which N-oxide serves as the intramolecular oxidizing agent. The solid-phase synthesis plays a critical role in the successful transformation, allowing rapid access to the unstable but Baeyer-Villiger oxidation-prone intermediate. This synthetic route provides practical access to 2-alkyl-2H-indazol-3-yl benzoates and 2-alkyl-1,2-dihydro-3H-indazol-3-ones, which are known privileged structures possessing remarkable diverse pharmacologically relevant activities.
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http://dx.doi.org/10.1021/acs.joc.6b00251 | DOI Listing |
Int J Biol Macromol
January 2025
College of Bioscience and Bioengineering, Fuzhou University, Fuzhou 360105, China. Electronic address:
Baeyer-Villiger monooxygenases (BVMOs) can catalyze the asymmetric sulfoxidation to form pharmaceutical prazoles in environmentally friendly approach. In this work, the thermostable BVMO named PockeMO had high sulfoxidation activity towards rabeprazole sulfide to form (R)-rabeprazole but demonstrated significant overoxidation activity to form undesired sulfone by-product. To address this issue, the enzyme was engineered based on the computer assisted comparison for the substrate binding conformations.
View Article and Find Full Text PDFJ Org Chem
January 2025
Center for Analysis and Synthesis, Department of Chemistry, Lund University, Lund SE 221 00, Sweden.
A diastereospecific synthesis of vicinally substituted 2-oxazolidinones from α,β-unsaturated lactams using -chloroperoxybenzoic acid is reported. Several highly substituted 2-oxazolidinones were obtained in 19-46% yields in a one-pot reaction with complete control over the relative stereochemistry. The proposed reaction sequence consists of a Baeyer-Villiger oxidation, an epoxidation, and a concerted rearrangement.
View Article and Find Full Text PDFPhytochemistry
January 2025
School of Food Science and Pharmaceutical Engineering, Testing & Analysis Center, Nanjing Normal University, Nanjing, 210023, China. Electronic address:
Fifteen sesquiterpenoids, including five previously undescribed monomers with oxidative rearranged skeletons (sarglabenoids A-E, 1-5) and three previously unreported lindenane [2 + 2] dimers (sarglabenoids F-H, 6-8), alongside seven related precursors (9-15), were isolated from the root of Sarcandra glabra. The structures of these compounds were elucidated using a combination of high-resolution electrospray ionization mass spectrometry, one-dimensional and two-dimensional nuclear magnetic resonance spectroscopy, the circular dichroism exciton chirality method, electronic circular dichroism, and nuclear magnetic resonance calculations integrated with DP4+ analysis. Compounds 1 and 2 feature an unique 5/5 spiro ring system, which is likely derived from a pinacol rearrangement of precursor 14.
View Article and Find Full Text PDFInorg Chem
December 2024
Henan Key Laboratory of Polyoxometalate Chemistry, College of Chemistry and Molecular Sciences, Henan University, Kaifeng, Henan 475004, P. R. China.
Directed synthesis of high-efficiency visible photoinduced Baeyer-Villiger oxidation catalysts is of primary significance. Here, the isopolymolybdate anion [β-MoO] is for the first time encapsulated with the photosensitive metalloligand [Ru(bpy)(Hdcbpy)] (bpy = 2,2'-bipyridine; Hdcbpy = 2,2'-bipyridine-5,5'-dicarboxylic acid) to synthesize polyoxometalate@metal-organic frameworks, {(CdDMF)[Ru(bpy)(dcbpy)]([β-MoO])}·5DMF (Ru-Mo). The composite photocatalyst Ru-Mo not only has a light absorption of 700 nm but also shortens the photogenerated electron transfer distances and accelerates charge and proton transfer.
View Article and Find Full Text PDFMolecules
December 2024
Institute of Chemistry, Moldova State University, 2028 Chisinau, Moldova.
The synthesis of tetra- and pentanorlabdane compounds with rearranged cycle B based on commercially available (+)-sclareolide is reported. Desired compounds were prepared from intermediate ketones via Baeyer-Villiger oxidation. The structures of synthesized compounds were confirmed by spectral IR, 1D (H, C, and DEPT), and 2D (H-COSY, H,C-HSQC, H,C-HMBC, H,N-HMBC, NOESY) NMR analyses, mass-spectrometry and single crystal X-rays diffraction.
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