Notes

Abstract

Amberlite IR-12O(H) ion-exchange resin (0-5 g., dried) was added to a mixture of redistilled 2 : 3-dihydropyran (17 g.) and ethyl glycollate (10 g.). The temperature rose slowly from 22" to 26". The mixture was kept for 20 hr. at room temperature, then filtered, and the filtrate was distilled as before.The amide was prepared by treatment of the ester with an excess of ammonia solution (d 04380) overnight. It crystallised after removal of solvent under reduced pressure and recrystallised from benzene as prisms, m.

Oxidative cleavage of β-aryl alcohols using manganese(IV) oxide

“…α-Aryl aldehyde 3 is known to polymerize when heated. 5 Compound 3 or 4 react again through oxidation to give α-hydroxy, α-aryl aldehyde 5. This can be cleaved to the corresponding product 6 either in the presence of AIBN and by a radical pathway or again by further oxidation by manganese(IV) oxide.…”

“…• with olefins as substrates for the cleavage of olefins or for the aromatization of cyclic olefins, 30,39,41,42 • with amines as substrates, oxidation to amides, imines 40 or with N-N coupling to diazo compounds, 5 • with diphenyl methanes as substrates, leaeding to oxidation to benzophenone 43 or with oxidative dimerization to 1,1,2,2-tetraphenylethane, 44 • with aromatic aldehydes as substrates leading to oxidation to carboxylic acids 5 , • with phosphines as substrates leading to oxidation to phosphine oxides. 5 Barakat et al has shown that carboxylic acids (Table 1, entries 1-6), α-hydroxycarboxylic acids (Table 1, entries 7-9) or α-aminocarboxylic acids (Table 1, entries 10-13) react with Mn(IV) oxide with decarboxylation or with ammonia elimination producing the corresponding carbonyl compounds (Table 1). Barakat et al assumed that the formation of ethylene from two citric acid molecules occurs through the reaction of two carbene intermediates.…”

“…5 a The yields are not given in the literature. 5 The corresponding carbonyl compounds or carbon dioxide are formed during the oxidation of alcohols or 1,2-diols with manganese dioxide (Table 2). 5 a The yields are not given in the literature.…”

“…1 The oxidation of organic compounds requires activated Mn(IV) oxide, for the preparation of which several methods have been reported. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] Depending on the preparative method, the structure, composition and the reactivity of the active Mn(IV) oxide changes. The efficiency of active Mn(IV) oxide strongly depends on the percentage of the γ-form.…”

“…In this step, α-aryl aldehyde 3 can polymerize. α-Aryl aldehyde 3 is known to polymerize when heated 5. Compound 3 or 4 react again through oxidation to give α-hydroxy, α-aryl aldehyde 5.…”