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Diethylacetal, oxidation

Schroder and co-workers studied the addition of formaldehyde-O-oxide, generated in situ at low temperature by ozonolysis of ketene diethylacetal, to the tropolonic ring of various colchicine analogues, Fig. (4) [80]. The intermediate ozonide E formed from 4 decomposed upon warming to give A-acetylcolchinol methyl ether 32 via the presumed intermediate F, in 81% yield. [Pg.367]

Naturally, it is possible to synthesise a similar ligand system without central chirality and in fact without the unnecessary methylene linker unit. A suitable synthesis starts with planar chiral ferrocenyl aldehyde acetal (see Figure 5.30). Hydrolysis and oxidation of the acetal yields the corresponding carboxylic acid that is transformed into the azide and subsequently turned into the respective primary amine functionalised planar chiral ferrocene. A rather complex reaction sequence involving 5-triazine, bromoacetal-dehyde diethylacetal and boron trifluoride etherate eventually yields the desired doubly ferrocenyl substituted imidazolium salt that can be deprotonated with the usual potassium tert-butylate to the free carbene. The ligand was used to form a variety of palladium(II) carbene complexes with pyridine or a phosphane as coligand. [Pg.304]

Recently, the group of Deffieux181 presented the synthesis and solution properties of macrocyclic poly-(styrene-/rethylene oxide). The synthetic route involved the preparation of a linear a-diethylacetal-a -styrenyl poly(styrene-b-ethylene oxide) precursor and cyclization by cationic activation with SnCh catalyst. The a-diethylacetal-poly(styrene-/rethyl-ene oxide) precursor was synthesized by using a-di-ethylacetalpropyllithium as initiator of styrene. The functional living PS was end-capped with ethylene oxide, and the resulted cu-hydroxyl group was reacted with diphenylmethylpotassium. The potassium alkox-... [Pg.602]

The smaller TON (calculated for ethylbenzene oxidation) and the lower conversion in ethanol is due to the oxidation of the solvent itself, as already reported [18]. The main product of ethanol oxidation is diethylacetal formed by initial oxidation of the alcohol to acetaldehyde and further nucleophilic addition and substitution with other alcohol molecules. Some amount of acetic acid and acetaldehyde are also observed in the reaction mixture. However, the... [Pg.913]

ACETALDEHYDE DIETHYLACETAL (105-57-7) Forms explosive mixture with air (flash point —5°F/—20°C cc). Reacts violently with oxidizers. Forms unstable and explosive peroxides on contact with heat and light. Flow or agitation of substance may generate electrostatic charges due to low conductivity. [Pg.2]

Quinoxaline-2-carboxaldehyde has been converted into the 2-carboxylic acid by oxidation with potassium permanganate in acetone and reduced to the 2-hydroxymethyl compound by treatment with formalin and potassium hydroxide. It also undergoes other typical reactions of aromatic aldehydes such as benzoin formation on reaction with potassium cyanide - and condensation reactions with malonic acid and its diethyl ester and Schiff base formation. Acid-catalyzed reaction of quinoxaline-2-carboxaldehyde with ethylene glycol gives the cyclic acetal the diethylacetal has been prepared by reaction of 2-dibromomethylquinoxaline with sodium ethoxide. " An indirect preparation of the oxime 11 is achieved by treatment of 2-nitromethyl-quinoxaline (10) with diazomethane followed by thermolysis of the resulting nitronic ester. [Pg.125]

The introduction of a nonenolizable substituent on nitrogen allows the separation of 5-carboxylic acids and their derivatives. Such compounds have been prepared in a variety of ways, including the oxidation of alkyl groups (Eq. 15) or formyl groups (Eq. 16). Sheehan and Robinson carried out a similar reaction sequence (Eq. 17) using a diethylacetal. ... [Pg.91]

The synthesis of 4-carboxyl-1,2,3-triazoles and derivatives has been an active field of study, and the variety of methods developed is impressive. One of the earliest reactions is the oxidation, usually with silver oxide, of the formyl group (Eq. 21). Sheehan and Robinson have reported the first example of phenyl azide addition in which both isomeric products were isolated (Eq. 22), and they demonstrated the structures of 4.2-1 and 4.2-2 by oxidation. Similar results were obtained using the diethylacetal of propy-nal followed by hydrolysis. [Pg.93]

Vanillin (3.04 g, 0.02 mol), dissolved in a minimum amount of absolute ethanol, was combined with 2.66 g of aminoacetaldehyde diethylacetal (0.02 mol), and the mixture was diluted to 15 mL with absolute ethanol and hydrogenated at atmospheric pressure and room temperature over 200 mg of previously reduced platinum oxide. Hydrogen consumption stopped at about 90% completion after about 3 h. The catalyst was removed by filtration and the solvent was evaporated under vacuum. The residual oil was dissolved in 50 mL concentrated hydrochloric acid. The solution which had become hot was cooled and washed with three 30-mL portions of 3 2 ether-benzene to remove starting aldehyde. A two-fold excess of benzaldehyde (4.24 g, 0.04 mole) dissolved in 50 mL of ethanol was added to the acidic solution which was subsequently boiled for 30 min. The cooled solution was diluted with an equal volume of water and washed with three 50-mL portions of ether to remove the excess benzaldehyde. The solution was made basic with ammonium hydroxide to pH 8. The precipitate was removed by filtration and crystallized once from water-ethanol to give 3.33 g of 4-benzyl-6-hydroxy-7-methoxyisoquinoline, in a yield of 63%, m.p. 185-190°C. The analytical sample has m.p. at 192-193°C. [Pg.443]

Oxidative carbonylation was coupled with reduction to afford catalytic carbonylation (see also Sect. VI.4.4.2). Thus, the diethylacetal of 2-propynal was carbonylated in a 65% yield by combining oxidative dicarbonylation and reductive splitting of an ethoxy group (Scheme 34). [Pg.957]


See other pages where Diethylacetal, oxidation is mentioned: [Pg.822]    [Pg.39]    [Pg.135]    [Pg.39]    [Pg.508]    [Pg.259]    [Pg.183]    [Pg.148]    [Pg.66]   
See also in sourсe #XX -- [ Pg.472 ]




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