Oxidation of furans - I. synthesis of 6-hydroxy-2H-pyran-3(6H)-ones

Titanium Silicalite 1 (TS‐1) Catalyzed Oxidative Transformations of Furan Derivatives with Hydrogen Peroxide

“…[13] Not surprisingly, a variety of procedures has been reported for their preparation starting from furfuryl alcohols. The three most widely used stoichiometric methods include oxidation with Nbromosuccinimide (NBS), [14] peroxy acids [15] and Br 2 in methanol. [16] Only few catalytic procedures are known.…”

“…Products were identified by comparison of their GC retention times with authentic samples prepared by m-CPBA oxidation. [11,15] Additionally, GC-MS and NMR were used to confirm the identity of the products. A Fisons GC 8000 Series gas chromatograph equipped with a 0.32 mm i.d.…”

“…Oxidation of furan compounds with m-CPBA [11,15] : Furan and its derivatives (1 mmol) were added to a solution of m-CPBA (0.5 or 1 mmol) in CH 2 Cl 2 (1 mL) at 0 8C. After reaction, precipitated m-chlorobenzoic acid was removed and the sample was subjected to GC and GC-MS analysis.…”

Pyrrolo[1,2-a]quinoxalines based on pyrroles (Review)

“…Boiling of 6-hydroxy-6-(2,3,5-tri-O-benzoyl-β-D-ribofuranosyl)-2H-pyran-3-one (101) (obtained by the oxidation of 2-hydroxymethyl-5-(2,3,5-tri-O-benzoyl-β-D-ribofuranosyl)furan with m-chloroperbenzoic acid [53] or pyrazinium chlorochromate [54]), and o-phenylenediamine for 2 h in chloroform gives a 43% yield of the quinoxaline derivative 103 and a 16% yield of the pyrrolo[1,2-a]quinoxaline derivative 102; a plausible mechanism for the formation of the latter probably involves nucleophilic attack by the o-phenylenediamine at the carbonyl group of the pyran ring in compound 101 followed by the formation of the Schiff's base 104, which opens under the reaction conditions, giving the imino ketone 105. Compound 105 undergoes cyclization to the enolic form 106 and is converted, after dehydration, into the tricycle 102 (path a).…”

Silicon-Tethered Intramolecular [5+2] Oxidopyrylium-Based Cycloaddition and Reductive Cleavage of Ether Bridge: Synthetic Studies Toward Arteminolides

“…ary carbon framework for the intermediate 13 by replacement of the TBS group with vinylsilyl group in two step operation. Oxidation-rearrangement of 18 using mCPBA, 8 followed by acetylation of the resulting tertiary hydroxyl group produced pyran 19 as a precursor to the oxidopyrylium ion. Oxidopyrylium ion was generated by treatment of pyran 14 with DBU in CH 2 Cl 2 and in situ [5+2] cycloaddition reaction proceeded via chair form of six-membered transition state 20 afforded the desired product 21 as a single diastereomer in 71% yield (Scheme 3).…”