A Simple Procedure for the Chromic Acid Oxidation of Alcohols to Ketones of High Purity

Brown, Herbert C.; Garg, C. P.

doi:10.1021/ja01474a037

Cited by 229 publications

(51 citation statements)

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“…An aliquot of the water recovered was taken for determination of tritium content. Chromic acid oxidation of monoterpenols and the synthesis of monoterpenol phenylurethane derivatives were carried out by standard procedures (6,10). The semicarbazone of [3H]menthone was prepared by dissolving 0.5 g of semicarbazide-HCl and 0.75 g of Na-acetate in 8 ml of water, followed by the addition of the ketone (0.5 g) and sufficient ethanol to make one phase.…”

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confidence: 99%

Metabolism of Monoterpenes

Croteau¹,

Martinkus²

1979

Plant Physiol.

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ABSTRACT(-)-Menthone, the major monoterpene component of the essential oil of maturing peppermint (Meathapiperita L.) laves (6 micromoles per leaf) is rapl metabolzed at the onset of flowering with a concomitant rise in the level of (-)-menthol (to about 2 micromoles per leaf). Exogenous (-)-HG3Hlmenthone is converted into (-)-I3HImenthol as the major steam-volatile product in kaf discs in flowering peppermint (10% of incorporated tracer); however, the major portion of the incorporated tracer (86%) resided in the novolatile metabolites of (-)-IG-'Hlmenthone. Acid hydrolysis of the nonvolatile material released over half of the radioactivity to the steamvolatile fraction, and the major component of this fraction was identified as (+)-neomenthol by radiochromatographic analysis and by synthesis of crystalline derivatives, thus suggesting the presence of a neomenthyl glycoside. Thin layer chromatography, ion exchange chromatography, and gel permeation chromatography on Bio-Gel P-2 allowed the purification of the putative neomenthyl glycoside, and these results suggested that the glycoside contained a single, neutral sugar residue. Hydrolysis of the purified glycoside, followed by reduction of the resulting sugar moiety with NaB%H4, generated a single labeled product that was subsequentiy identified as glucitol by radio gas-liquid chromatography of both the hexatrimethylsilyl ether and hexaacetate derivative, and by crystallization to constant specific radioactivity of both the alditol and the corresponding hexabenzoate. These results, along with studies on the hydrolysis of the glycoside by specific glycosidases, strongly suggest that (+)-neomenthyl-/8-D-glucoside is a major metabolite of (-)-menthone in flowering peppermint. This is the first report on the occurrence of a neomenthyl glycoside, and the first evidence implicating glycosylation as an early step in monoterpene catabolismL While monoterpenes were once regarded as metabolically inert "secondary products" (17), considerable evidence, based on both short term tracer studies and long term periodic analyses, now indicates that monoterpenes are, in fact, metabolically active and subject to rapid turnover in plants (15 Evidence for monoterpene turnover in peppermint (Mentha piperita L.) has been obtained by periodic analysis of plants grown under controlled conditions (7). In these studies, midstem leaves accumulated high levels of (-)-menthone until the time of floral initiation, and then lost much of the menthone. Previous evidence has indicated that (-)-menthone can be converted to (-)-menthol (4,5,18) and (-)-menthyl acetate (9) in mint and, during the period of menthone catabolism, a portion of the menthone appeared to be converted to these metabolites. However, the quantity of menthol and menthyl acetate formed was not sufficient to account for the amount ofmenthone lost, and no other metabolites of menthone have been identified. Here we describe, for the first time, the identification of (+)-neomenthyl-,6-D-glucoside as a major metabolite of (-)-mentho...

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confidence: 99%

Metabolism of Monoterpenes

Croteau¹,

Martinkus²

1979

Plant Physiol.

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“…Next, the hydroxyl group was converted to carbonyl group by oxidation with potassium dichromate (VI). Reaction was carried out applying Brown-Garg methodology and isopinocamphone was obtained in high yield [6].…”

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confidence: 99%

<strong>New approach for the synthesis of pinane derived bisphosphines</strong>

Kmieciak

Kołodziej

Krzemiński

2017

Proceedings of the 21st International Electronic Conference on Synthetic Organic Chemistry

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“…17 The oxidation of chromanols 2a,b to chromanones 3a,b in 74-79% yields was performed with chromic acid (from sodium dichromate and sulfuric acid) in ethyl ether. 18 Dehydration of chromanol 2a was effected by a trace of p-toluene sulfonic acid in boiling benzene for 5 h and subsequent distillation of the reaction mixture gave 2-(trifluoromethyl)-2H-chromene 4 in 70% yield, which was sensitive to oxygen of air. Surprisingly, as in the case of 2-(trifluoromethyl)chroman-4-one 3a, whose isolation and characterization had not been reported prior to our work, 12 none of these simple compounds was recorded in the literature.…”

Section: Resultsmentioning

confidence: 99%