Hexanones, from oxidation

Iffland and Criner [209] have improved the method. They obtained nitrocyclo-hexanone from cyclohexanone in about 50% yield, using N-bromosuccinimide as an oxidizing and brominating agent. 

Can we pursue either of the fragments arising from disconnection by pathway c to even simpler starting materials Yes recall (Section 8-6) that ketones are obtained from the oxidation of secondary alcohols by Cr(VI) reagents. We may therefore envision preparation of 3-hexanone from the corresponding alcohol, 3-hexanol. 

Methylsuccinic acid has been prepared by the pyrolysis of tartaric acid from 1,2-dibromopropane or allyl halides by the action of potassium cyanide followed by hydrolysis by reduction of itaconic, citraconic, and mesaconic acids by hydrolysis of ketovalerolactonecarboxylic acid by decarboxylation of 1,1,2-propane tricarboxylic acid by oxidation of /3-methylcyclo-hexanone by fusion of gamboge with alkali by hydrog. nation and condensation of sodium lactate over nickel oxide from acetoacetic ester by successive alkylation with a methyl halide and a monohaloacetic ester by hydrolysis of oi-methyl-o -oxalosuccinic ester or a-methyl-a -acetosuccinic ester by action of hot, concentrated potassium hydroxide upon methyl-succinaldehyde dioxime from the ammonium salt of a-methyl-butyric acid by oxidation with. hydrogen peroxide from /9-methyllevulinic acid by oxidation with dilute nitric acid or hypobromite from /J-methyladipic acid and from the decomposition products of glyceric acid and pyruvic acid. The method described above is a modification of that of Higginbotham and Lapworth. ... 

Fermenting baker s yeast also catalyzes the 1,4-addition of a formal trifluoroethanol-d1-synthon to a,/i-unsaturated aldehydes, to give optically active l,l,l-trifluoro-2-hydroxy-5-alka-nones52. Presumably, the mechanism involves oxidation of the alcohol to the corresponding aldehyde followed by an umpolung step with thiamine pyrophosphate and Michael addition to the a,/i-unsaturated aldehyde. For example, l,l,l-trifluoro-2-hydroxy-5-hexanone (yield 26%, ee 93%) is thus obtained from trifluoroethanol and l-bnten-3-one. 

This forecasts that should k[Cr(VI)] considerably exceed kjj then a change of reaction order with respect to Cr(VI) from one to zero is to be expected. This they observed for isobutyrophenone in 99 % acetic acid and 2-chlorocyclo-hexanone in water at moderate concentrations of oxidant. 

In reactions carried out for 24 h at room temperature, a 95% yield of cyclo-hexanol from cyclohexanone was obtained. Other ketones and aldehydes were also hydrogenated under identical conditions, but with slower rates (38% conversion for hydrogenation of 2-hexanone, 25% conversion of acetophenone, 45% for 3-methyl-2-butanone). Insertion of the C=0 bond of the ketone or aldehyde into the Cr-H bond was proposed as the first step, producing a chromium alk-oxide complex that reacts with acid to generate the alcohol product. The anionic chromium hydride [(COJsCrH]- is regenerated from the formate complex by... 

Branchflower and Pohl (1981) postulated that this depletion might be associated with the potentiation of toxic effects from chloroform (CHCP) when coadministered with 2- hexanone, since depletion of hepatic GSH could allow more phosgene (COCI2) (the toxic oxidation product of chloroform) to react with sensitive tissue components. 

Wittig reactions of cyclohexanone derivatives in their inclusion compounds with the chiral host 5 gave optically active reaction products. For example, when a mixture of finely powdered 1 1 inclusion compound of 5b with 4-methyl-(15a) or 4-ethylcyclo-hexanone (15b) and phosphorane (16) was kept at 70 °C, the Wittig reaction in the solid state was completed within 4 h. To the reaction mixture was added diethyl ether-petroleum ether (1 1), and then the precipitated triphenylphos-phine oxide was removed by filtration. The crude product left after evaporation of solvent from the filtrate was distilled in vacuo to give (-)-4-methyl- (17a) of 42% ee (73 % yield) or (-)-4-ethyl-l-(carboethoxymethylene)cyclohexane (17b) of 45 % ee (57 % yield), respectively [9], Similar reaction of the 1 1 inclusion compound of 5c and c /. v - 3,5 - dime th y I c y c I o h e x a n o n e (18) with 16 gave 19 of 57 % ee in 58 % yield [9],... 

Zr has been separated from Hf with the use of TBP in 4 M HNO3 [21]. These metals can also be separated in thiocyanate medium with the use hexanone as extractant. Ion-pairs of thiocyanate complexes of Zr and Hf with antipyrine and DAM were separated by extraction (isoamyl alcohol, 1,2-dichloroethane) from other metals [22]. Zirconium can be extracted first with mesityl oxide from a 4 M solution (in HNO3 and NaNOs), then hafnium is extracted from 0.4 M HNO3 and 2 M NH4SCN medium [23]. 

Oxidation of 2-hexanol from part (c) yields 2-hexanone. 

Finally, oxidative carbonylations of simple ketones, such as hexanone and pentanone, were reported to give diesters [42,43]. In the presence of PdCl2, CUCI2, CO, and in methanol, various diesters have been produced in good yields from corresponding cyclic ketones. 

Dimethylsulfonium methylide [(CH3)2S CH2 ] is the more reactive of the pair and is both prepared and used at lower temperature than its more highly oxidized analogue, en it reacts with a cyclic ketone such as 4-(l,l-dimethylethyl)cyclo-hexanone (4-t-butylcyclohexanone), addition occurs primarily (ca. 80 20) from the axial direction, and subsequent elimination of dimetihyl sulfide [(CH3)2S] leads to the corresponding epoxide (oxirane) (Scheme 9.55). 

In an aptly titled paper Herz et describe unexpected rearrangements of photolevopimaric acid derivatives. Among a wealth of chemical reactions discussed it appears that the exo-bicyclo[2,2,0]hexanol (575), derived from methyl levopimarate by hydroboration-oxidation, is rearranged during Jones oxidation to the bicyclo[2,l,l]-hexanone (576), contrary to a previous report. A mechanism is proposed. 

Hexanone can be synthesized from 3-hexanol, which can be synthesized from a three-carbon aldehyde and a three-carbon Grignard reagent. Oxidation of 1-propanol forms the three-carbon aldehyde, and conversion of 1-propanol to a propyl halide allows the three-carbon Grignard reagent to be synthesized. 

Many reports of selenium relate to its use as a source of double bonds. Continuing this theme, phenols are formed from cyclohexenones by phenyl-selenation (PhSeCl) and oxidative removal of the selenyl group (MCPBA). In their turn cyclohexenones have been prepared by a similar sequence. The interesting point here is that the double bond can be inserted at the less substituted conjugated position by base isomerization of the phenylselenocyclo-hexanone. For example, the phenylseleno-group in the cyclohexanone (283)... 

Hydrolysis of the labeled compound with 2 N sulfuric acid furnished 3-amino-4-methyl-2-hexanone which, on treatment with iodine in the presence of sodium hydroxide, furnished isoleucine and iodoform. The iodoform was oxidized to carbon dioxide, while treatment of isoleucine with ninhydrin furnished 2-methylbutanal, isolated as its 2,4-dinitrophenylhydrazone. Kuhn-Roth oxidation of the aldehyde gave acetic acid which was degraded by the Schmidt procedure to carbon dioxide and methylamine. The 2-methylbutanal was also degraded stepwise by the method of Strassman. Determination of the radioactivity of the various degradation products showed that 94% of the activity was equally shared between the lactam C(2) and side-chain C(10) carbonyl atoms. The remaining activity was shared between C(4) of the lactam ring and the a> carbon atom of the ec-butyl side chain. The results are consistent with derivation of tenuazonic acid from isoleucine and two molecules of acetic acid. However, the direct incorporation of isoleucine into tenuazonic acid was not investigated. 

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