Improved procedure for oxidations with the chromium trioxide-pyridine complex

Ratcliffe, Ronald W.; Rodehorst, R. M.

doi:10.1021/jo00836a108

Cited by 578 publications

(195 citation statements)

References 2 publications

Supporting

Mentioning

188

Contrasting

Unclassified

Order By: Relevance

“…Tetrahymanol was acetylated (Rohmer et al, 1984), and its acetate purified by TLC using cyclohexane/ethyl acetate (98:2, v/v) as solvent system, in which RF = 0.25. Tetrahymanone was obtained by CtO3/pyridine oxidation in methylene chloride (Ratcliffe & Rodehorst, 1970) and separated by TLC using methylene chloride as eluent, in which RF = 0-35. …”

Section: Methodsmentioning

confidence: 99%

Tetrahymanol from the phototrophic bacterium Rhodopseudomonas palustris: first report of a gammacerane triterpene from a prokaryote

Kleemann

Poralla

Englert

et al. 1990

Journal of General Microbiology

130

View full text Add to dashboard Cite

show abstract

Section: Methodsmentioning

confidence: 99%

Tetrahymanol from the phototrophic bacterium Rhodopseudomonas palustris: first report of a gammacerane triterpene from a prokaryote

Kleemann

Poralla

Englert

et al. 1990

Journal of General Microbiology

130

View full text Add to dashboard Cite

show abstract

“…The polyprenols (12 mg) were oxidized by Cr03/pyridine complex in dry CH2C12 [15] giving a mixture of the corresponding cisltrans aldehydes. These aldehydes were not separated and an aliquot (2 mg) was reduced overnight at room temperature with NaB3H4 (total activity 5 mCi, specific activity 15 Ci/mmol) in dry /--. Fig.…”

Section: Synthesis Of [L-3h/polyprenyl Methyl Ethers ( I ) and (3)mentioning

confidence: 99%

Enzymatic cyclization of all‐trans pentaprenyl and hexaprenyl methyl ethers by a cell‐free system from the protozoon Tetrahymena pyriformis

Renoux¹,

Rohmer²

1986

European Journal of Biochemistry

View full text Add to dashboard Cite

A cell-free system from the protozoon Tetrahymenapyriforrnis capable of cyclizing squalene into tetrahymanol cyclizes all-trans pentaprenyl methyl ether to a scalarane-type sesterterpene and all-trans hexaprenyl methyl ether to bicyclo-, tricyclo-, tetracyclo-and pentacyclohexaprenyl methyl ethers, each corresponding to a possible cationic intermediate. The structures of the cyclization products have been determined by spectroscopic methods and are compatible with a biogenetic scheme involving polyprenyl ether cyclization. This is the first direct proof of an enzymatic cyclization of higher isoprenic alcohol derivatives, and we assume it was performed by the squalene-to-hopane cyclase of the protozoon. The formation of a scalarane-type sesterterpene from CZ5 polyprenyl methyl ether suggests that these terpenoids, whose presence is restricted to a few sponges, might be in fact microbial metabolites. Tricyclopolyprenyl derivatives have been identified in the organic matter from numerous sediments and they were interpreted as being chemical fossils of still unidentified microorganisms. The cyclization of hexaprenyl methyl ether is the first attempt of identification of these tricyclopolyprenol derivatives in living organisms.Some of the numerous microbial lipids have been discovered after the identification of their chemical fossils dispersed in the organic matter of sediments [l]. The ubiquitous geohopanoids are the most striking example: they have been found to be present, varied and abundant, in all sediments analyzed up to now, and they were found to be the molecular fossils of a new class of widespread and varied prokaryotic lipids, the microbial hopanoids [2, 31. The existence of other new classes of microbial lipids has been postulated by us from the wide distribution of still 'orphan' chemical fossils, plausible precursors of which were unknown in extant microorganisms [l]. These included, for instance, aliphathic glycerol ethers similar to the archaebacterial lipid ethers, the pentacyclic triterpene isoarborinol and the tricyclopolyprenols. The existence of the latter compounds in microorganisms was suggested by the identification of tricyclic sedimentary hydrocarbons in the CI9 to C45 range' [4-71. Biogenetically, these isoprenoids can be deduced from a proton-catalyzed cyclization of suitable regular polyprenol derivatives giving tricyclic compounds, the structures of which resemble those of some natural sesterterpenes isolated from a fern or a nudibranch [8,9]. Such cyclizations have already been studied in the biosynthesis of lower homologues from the mono-, sesqui-and diterpene series.Correspondence to M. Rohmer, Ecole Nationale Superieure de Chimie de Mulhouse, 3 rue Alfred Werner, F-68093 Mulhouse Cedex, France A bbreviutions. TLC, thin-layer chromatography; GLC, gas-liquid chromatography; MS, mass spectrometry; NMR, nuclear magnetic resonance.In an attempt to detect these isoprenoids in living organisms, we tried to cyclize tritium-labelled all-trans pentaprenol and hexaprenol derivatives with cell...

show abstract

“…Oxidation of 3-methyl-2-butenol (Aldrich) was carried out using Ratcliffe's method (17). To a solution of pyridine (9.5 g) in dry methylene chloride (passed through Grade I neutral alumina) (150 mL) was added chromium trioxide (6 g).…”

Section: Preparation Of3-methyl-2-butenal I Cmentioning

confidence: 99%

The retroaldol reaction of 3-methyl-2-butenal

Guthrie¹,

Dawson²

1983

Can. J. Chem.

View full text Add to dashboard Cite

Can. J. Chem. 61, 171 (1983). In aqueous sodium hydroxide solutions at 25OC, 3-methyl-2-butenal, I c , undergoes retroaldol cleavage to acetone and acetaldehyde. The kinetics of thc rctroaldol reaction wcrc followed spectrophotometrically at 242 nm and showed simple first order behavior. When 3-methyl-3-hydroxybutanal, 2c, was added to aqueous sodium hydroxide solutions at X°C, there was an initial increase in absorbance at 242 nm, attributed to formation of l c , followed by a 20-fold slower dccrcase; the rate of the slow decrease matches the rate of disappearance of l c under the same conditions. Analysis of the kinetics allows determination of the three rate constants needed to describe the system: kl,,, = 0.00342; kdchy,, = 0.00832; k,,,, = 0.0564; all M-' s-I. The equilibrium constant for enone hydration is 0.41. Rate constants for the analogous reactions for acrolein and crotonaldehyde could be obtained from the literature. There is a reasonable rate-equilibrium correlation for the retroaldol step. For the enone hydration step, rate and equilibrium constants respond differently to replacement of hydrogen by methyl. It is proposed that this results from release of strain after the rate-determining step by rotation about a single bond; this decrease in strain is reflected in the equilibrium constant but not in the rate constant.J. PETER GUTHRIE et BRIAN A. DAWSON. Can. J. Chem. 61, 171 (1983). Le methyl-3 buttnal-2 ( l c ) , dans des solutions aqueuses d'hydroxyde de sodium a 25"C, subit un clivage rCtroaldolique conduisant a I'acttone et I'acCtaldChyde. On a suivi spectrophomCtriquement a 242 nm la cinCtique de cette rtaction simple d'ordre un. Lorsqu'on ajoute du mCthyl-3 hydroxy-3 butanal (2c) des solutions aqucuses d'hydroxyde de sodium 5 25"C, il y a une augmentation initiale de I'absorption 2 242 nm que I'on attribue la formation du compost I c suivie d'une diminution qui est 20 fois plus lente; le taux de la faible diminution correspond au taux de disparition du produit l c dans ces rn&mes conditions. L'analyse des donnCes cinttiques permet de dtterminer les trois constantes de vitesse necessaires a la description Introduction We have reported a study (1) of the equilibrium constants for aldol condensation reactions. It seemed highly desirable to look for rate-equilibrium correlations for these synthetically important reactions, particularly since equilibrium constants were now available. However, there have been comparatively few kinetics investigations of aldol reactions. This is in large measure due to the great potential for complexity for most aldol reactions, with various modes of reaction, competing equilibria, and polymerization leading to hopelessly complicated mixtures. We have shown that much of this complexity can be avoided by studying the retroaldol reaction at low concentrations, in a study of the reaction of crotonaldehyde in dilute aqueous base (2). We now wish to report a study of a closely related compound with one additional carbon methyl group, namely 3-methyl-2-butenal, l c . Th...

show abstract

Improved procedure for oxidations with the chromium trioxide-pyridine complex

Cited by 578 publications

References 2 publications

Tetrahymanol from the phototrophic bacterium Rhodopseudomonas palustris: first report of a gammacerane triterpene from a prokaryote

Tetrahymanol from the phototrophic bacterium Rhodopseudomonas palustris: first report of a gammacerane triterpene from a prokaryote

Enzymatic cyclization of all‐trans pentaprenyl and hexaprenyl methyl ethers by a cell‐free system from the protozoon Tetrahymena pyriformis

The retroaldol reaction of 3-methyl-2-butenal

Contact Info

Product

Resources

About