A novel approach has been developed
for the synthesis of a wide
range of α-ketoacetals by the reaction of alkyl/aryl methyl
ketones and aliphatic alcohols in the presence of selenium dioxide
catalyzed by
p
-toluenesufonic acid. This method represents
a general route to obtain a wide variety of α-ketoacetals in
a simple, rapid, and practical manner. This approach is particularly
attractive because of the easy availability of the starting materials,
mild reaction temperature, and good yields of the products. The resulting
α-ketoacetals are of much synthetic value as organic intermediates.
A general strategy for the preparation of N, N-dialkyl-2-oxo-2-arylethaneselenoamides is described. The single step method involves direct coupling of aryl methyl ketones with secondary amines and selenium dioxide in DMSO. The reactions proceeded smoothly at room temperature to provide a number of the α-oxo-selenoamides in good to excellent yields.
Single-crystal XRD data of 3a and copies of 1 H and 13 C NMR of all synthesized compounds (PDF)Accession Codes CCDC 2041476 contains the supplementary crystallographic data for this paper. These data can be obtained free of charge via www.ccdc.cam.ac.uk
A metal-free three-component coupling reaction of aryl alkyl/alkyl ketones, SeO 2 , and phenols/anisoles is described. This multicomponent reaction provides a straightforward and facile pathway for the synthesis of α-((4-hydroxy/methoxyphenyl)selanyl)-aryl alkyl/ alkyl ketones in the presence of p-toluenesulfonic acid for the C−Se bond formation process. The method offers an attractive and simple procedure using commonly available shelf reagents to deliver organoselenides that, to our knowledge, are being reported here for the first time.
All commercially available chemicals and reagents were purchased from Sigma Aldrich, Merck and were used without further purification. The synthesized compounds were characterized by FT-IR, 1 H NMR, 13 C NMR and mass spectrometry analyses. Melting points were recorded with open capillary tube method and are uncorrected. FT-IR spectra were recorded with KBr pellets using a Perkin-Elmer 400 Series FT-IR spectrometer. 1 H and 13 C NMR spectra were recorded on a Bruker Avance II-400 instrument operating at 400 MHz for protons, 100 MHz for carbon in dimethylsulfoxide (DMSO-d 6 ) as solvent (Chemical shifts in δ with tetramethylsilane (TMS) as internal standard. Electrospray ionization (ESI) mass spectra were recorded on a Waters ZQ-4000 LC-MS spectrometer. The progress of the reaction was monitored by thin-layer chromatography (TLC) analysis on pre-coated silica gel 60 F 254 aluminum sheets (Merck), visualized under UV-light.
X-ray CrystallographyThe CIF files containing the crystal structural data of 4g and 4i were deposited in the Cambridge Crystallographic Data Center and can be obtained free of charge on request from the Cambridge Crystallographic Data Center. https://www.ccdc.cam.ac.uk/structures/?The X-ray data of 4g and 4i were collected with a Agilent Xcalibur (Eos, Gemini) diffractometer using graphite monochromated Mo-K α radiation (λ = 0.71073 Å). The data was collected and refined in CrysAlis PRO (Rigaku, 2015) 1 software and data reduction was performed using the CrysAlisPro (Rigaku, 2015) software which corrects for Lorentz polarisation. A multi-scan absorption correction was performed using CrysAlisPro (Rigaku, 2015) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm. Using Olex2 2 , the structure was solved with the ShelXS 3 structure solution program using Direct Methods and refined with ShelXL-2018 4 using full matrix least squares on F 2 minimisation. All non-hydrogen atoms were refined anisotropically. Hydrogen atom positions were calculated geometrically and refined using the riding model. The ORTEP view of 4 (g & i) were illustrated by ORTEP-3 5 as shown in Figure 1.
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