Alkaline epoxidation of α,β-unsaturated aldehydes was written by Payne, George B.. And the article was included in Journal of Organic Chemistry in 1961.Category: tetrahydropyran This article mentions the following:
Using the previously described procedure, MeCH:CHCHO (I) was epoxidized to yield 77% flashed aqueous epoxy aldehyde, RCH.CR'(CHO).O (II, R = Me, R’ = H), which gave 56% anhydrous product. For epoxidation of relatively H2O-insoluble unsaturated aldehydes, MeOH was used as solvent. MeOH (300 ml.) containing 0.55 mole 30% H2O2 stirred at 35-40°, with cooling in a 5-necked flask provided with stirrer, dropping funnels, and standard electrodes attached to a Beckman pH meter, with dropwise addition in 10 min. of 56 g. 3-formyl-5,6-dihydro-2H-pyran (III) and addition of N NaOH to maintain meter pH 9 (corresponding to indicator paper pH 8), the mixture stirred 1.5 hrs. (consumption of 0.52 mole peroxide and 19 ml. N NaOH) and concentrated in vacuo, the concentrate saturated with (NH4)2SO4 and extracted 3 times with 150 ml. CHCl3, the washed (saturated (NH4)2SO4) and dried (MgSO4) extract concentrated, and the residue distilled through a glass helices-packed column yielded 70% epoxy aldehyde. In a similar flask 1 l. MeOH and 0.10 mole 30% H2O2 stirred with cooling at 35-40° 1 hr. with alternate portionwise addition of 132 g. PhCH:CHCHO (IV) in 100 ml. MeOH, 1.0 mole 30% H2O2, and N aqueous NaOH at constant meter pH 10.5-11.0 (pH 8-8.5 by indicator paper), the mixture kept 1 hr. at meter pH 10.0-10.5 and 35°, concentrated to 300 ml. and diluted with 1 l. H2O, extracted 3 times with 300 ml. Et2O and concentrated at 20° to constant weight (136 g. containing 0.08 mole organic peroxide), the residue taken up in 50 ml. C6H6 and hydrogenated 30 min. at 20°/50 lb./sq. in. with 3 g. 5% Pd-C, the filtered solution distilled and the product (79 g., b0.5 65-90°) redistilled through a 10-tray Oldershaw column yielded 24% β-phenylglycidaldehyde. Results obtained similarly with I, MeCH:CMeCHO, III, IV, and citral are summarized (R, R’ of II, or starting compound, % yield, b.p./mm., n20D, and m.p. of 2,4-dinitrophenylhydrazone given): Me, H, 56, 60-1°/80, 1.4179, 136-8°; Me, Me, 46, 58-9°/60, 1.4198, -; III, 70, 56-7°/2.0, 1.4739, 136-6.5°; Ph, H, 24, 70-2°/0.3, 1.5448, 138-9°; citral, 75, 63-7°/1.0, 1.4609, -. II from I, MeCH:CMeCHO, and citral are new compounds In the experiment, the researchers used many compounds, for example, 5,6-Dihydro-2H-pyran-3-carbaldehyde (cas: 13417-49-7Category: tetrahydropyran).
5,6-Dihydro-2H-pyran-3-carbaldehyde (cas: 13417-49-7) belongs to tetrahydropyran derivatives. Tetrahydropyrans and furans principally constitute as a central motif in diverse medicinally privileged molecules. The reaction of tertiary 1,4- and 1,5-diols with cerium ammonium nitrate at room temperature gives tetrahydrofuran and tetrahydropyran derivatives in high yield and stereoselectivity. Various fragrant compounds have been synthesized using this method.Category: tetrahydropyran
Referemce:
Tetrahydropyran – Wikipedia,
Tetrahydropyran – an overview | ScienceDirect Topics