Improved oxidation procedure with aromatic peroxyacids

Synthesis and Insecticidal Activity of Sesquilignan Analogs with 2-Alkyl-6-methoxy-3-(3,4-methylenedioxyphenyl)-1,4-benzodioxanyl Group

“…Propyl (7): Alcohol 5 (7.0 g, 16 mmol) in 2% sulfuric acid in acetic acid (75 ml) was heated for 10 min at 70-80°C. 6) The reaction mixture was decanted onto ice pieces (200 g) and extracted with ethyl acetate (100 ml).…”

Influence on Insecticidal Activity of the 3-(3,4-Methylenedioxyphenyl) Group in the 1,4-Benzodioxanyl Moiety of Haedoxan

“…After the aqueous layer had been acidified with sulfuric acid, it was re-extracted with ethyl acetate, and the organic layer was washed with 5% aqueous sodium bicarbonate. The combined organic solutions were dried and concentrated, and the residue was purified by column chromatography (EtOAc) to give diols 6 (11.8 g, 49 mmol, 83 %) as a colorless oil; 100 MHz NMR ( (7). To a stirred and cooled (-10°C) solution of diols 6 (11.8 g, 49 mmol) and pyridine (40 ml) in dichloromethane (40 ml) was added methanesulfonyl chloride (4.33 ml, 56 mmo!)…”

Investigation of the chemoselective and enantioselective oxidation of α-thio-β-chloroacrylamides

“…1 H NMR spectroscopy of the crude product mixture ‡ Yield after chromatography on silica gel § Enantiomer ratios were determined by chiral HPLC using IPA/hexane as mobile phase on a Chiralcel AS column detected at  254 nm  All optical rotations were recorded as solutions in DCM (c 1.3-2.0) ¶ As determined by chiral shift NMR spectroscopy using (+)-Eu(hfc) 3 as chiral shift reagent Significantly, oxidation is only observed for N-aryl derivatives, with partial or complete oxidation to the sulfoxides seen under the standard Kagan oxidation conditions, albeit with modest enantioselectivity.…”

“…Following the development of the vanadium catalysed process, Bolm has reported that aryl alkyl sulfides can be rapidly oxidised to give chiral sulfoxides with enantioselectivities up to 90% ee using an iron catalyst formed in situ from Fe(acac) 3 and Schiff base ligands 5g-5i. 36 Significantly, Bolm has reported improved stereoselectivities in the iron catalysed sulfide oxidation in the presence of additives such as substituted benzoic acids although use of these additives was not explored in this work.…”

“…A variety of oxidants have been employed for this transformation. 2 Among the more common oxidants are mCBPA, 3 The asymmetric synthesis of sulfoxides has received particular attention in recent years as the sulfoxide moiety has been shown to provide excellent stereochemical control as a chiral auxiliary. Also, many enantiopure sulfoxides are known to have high biological activity.…”