Oxidation of secondary alcohols in diethyl ether with aqueous chromic acid. Convenient procedure for the preparation of ketones in high epimeric purity

Brown, Herbert C.; Garg, C. P.; Liu, Kwang‐Ting

doi:10.1021/jo00802a005

Cited by 190 publications

(51 citation statements)

References 2 publications

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“…Ethyl tert-butyl ketone was prepared directly by the chromic acid two phase (ether-water) oxidation 19 of the corresponding alcohol (commercially available).…”

Section: Methodsmentioning

confidence: 99%

Enolboration 3. An Examination of the Effect of Variable Steric Requirements of R on the Stereoselective Enolboration of Ketones with R2BCl/Et3N. Bis(Bicyclo(2.2.2)Octyl)Chloroborane/Triethylamine - A New Reagent Which Achieves the Selective Generation of E Enolborinates from Representative Ketones

Brown¹,

Ganesan²,

Dhar³

1992

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“…Ethyl tert-butyl ketone was prepared directly by the chromic acid two phase (ether-water) oxidation 19 of the corresponding alcohol (commercially available).…”

Section: Methodsmentioning

confidence: 99%

Enolboration 3. An Examination of the Effect of Variable Steric Requirements of R on the Stereoselective Enolboration of Ketones with R2BCl/Et3N. Bis(Bicyclo(2.2.2)Octyl)Chloroborane/Triethylamine - A New Reagent Which Achieves the Selective Generation of E Enolborinates from Representative Ketones

Brown¹,

Ganesan²,

Dhar³

1992

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“…The solvent was removed and the residue (280 mg) was carefully chromatographed over silica gel. Hexane-THF (1O:l) elution gave 254 mg (90%) of the alcohol 8 containing a small amount of isomeric alcohols derived from 4 and 6 bp 78.0-80.0' (0.01 mm); ir (neat) 3410 (broad, OH) and 1735 cm-l; NMR (CDC13) 6 7-Methoxycarbonyl-2-norbornanone (9). The alcohol 8 (120 mg, 0.706 mmol) contaminated with the isomeric alcohols derived from 4 and 5 was dissolved in CHzC12 (5 ml) and cooled to 0-4" in an ice bath.…”

Section: Methodsmentioning

confidence: 99%

“…The combined extracts were washed with brine, dried (NazSOd), and concentrated. The residue was chromatographed over silica gel using hexane-THF (6:l) to give 9 (107 mg, 90%) containing a small amount of isomeric ketones derived from 4 and 5: bp 52.0-53.0' (0.01 mm); ir (neat) 1752 and 1741 cm-l (ester and ketone carbonyls); NMR (CDC13) 6 (10). 7-Carbomethoxy-2-norbornanone (9,168 mg, 1 mmol) contaminated with a small amount of the isomeric ketones was dissolved in ether (3 ml) containing monoperphthalic acidI6 (364 mg, 2 mmol) and the mixture was allowed to stand for 2 days at 17O.…”

Section: Methodsmentioning

confidence: 99%

Electrolytic decarboxylation reactions. II. Syntheses of methyl dihydrojasmonate and methyl dl-jasmonate from 3-methoxycarbonyl-2-carboxynorbornane via anodic acetoxylation

Torii¹,

Tanaka²,

Mandai³

1975

J. Org. Chem.

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Methyl dihydrojasmonate (la) and methyl dl-jasmonate (lb) were prepared from 3-methoxycarbonyl-2-carboxynorbornane (2a) via anodic acetoxylation. Electrolysis of 2a in a mixed solvent of AcOH-t-BuOH-EtsN gave a desired key intermediate, exo-2-acetoxy-anti-7-methoxycarbonylnorbornane (3), in 56% yield (GLC peak area) together with several minor products, 4 (12%), 5 (7%), 6 (ll%), and 7 (4%). Hydrolysis of 3 followed by oxidation with chromic acid afforded 7-methoxycarbonyl-2-norbornanone (9) in good yield. The Baeyer-Villiger oxidation of 9 and subsequent hydrolysis and oxidation gave 2-methoxycarbonyl-3-methoxycarbonylmethylcyclopentanone (12) in 54% yield. Alkylation of 12 with pentyl and 2-pentynyl bromide and following cis hydrogenation and demethoxycarbonylation afforded l a and lb, efficiently.In the preceding paper we reported the product-selective and chemically controlled electrolytic decarboxylation reaction involving the formation of either radical or carbonium ion intermediate.l We have now extended this electrochemical decarboxylation method to a novel acetoxylation reaction for the preparation of exo-2-acetoxy-anti-7-methoxycarbonylnorbornane (3), which is expected to be an intermediate for the methyl dl-jasmonate synthesis.2Although electrolysis of exo-and endo-norbornane-2-carboxylic acid in Et3N-MeOH has been shown to afford exo-2-methoxynorbornane in a sufficient yield via a carbonium intermediate: instead of alkoxides acetoxy derivatives have been generally considered to be more useful intermediates for synthetic purposes. Indeed, one of the precursors for the preparation of methyl dl-jasmonate (lb) must be the acetoxy compound 3, which may be derived from 2-methoxycarbonyl-3-carboxynorbornane by electrolytic acetoxylation. v:cooMe 0 la, R = n-CSH,, b, R = CH&H=CHEt-cis c, R = CH,CaCEt

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“…/ , 2,5,9,9-~evlfa~.~ef~z:~~l-spjroi3.51?1on-5- S.? (19), 69 ( 7 8 G',6'-trimethyl-cyclokex-a'-eiz-/'-yZide~z)-butniz-2-o~~ (10). -Sdp.…”

Section: Mitteilung In Der Ethz-reihe Photochcmische Kcaktionen [L]mentioning

confidence: 99%

Zur Photochemie des Iso‐methyl‐α, (E)‐jonons

Becker

Ehrenfreund

Jeger

et al. 1974

Helvetica Chimica Acta

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Summary. UV.-irradiation of iso-methyl-a, (E)-ionone (4) in neutral solvents yields iso-methyla, (2)-ionone ( 5 ) . the bicyclic ether 6 and the epoxidc 7 by a sequence of successive photoisomerizations. The steps leading to dcs-methyl homologues of 6 and 7 do not occur on irradiation of CI, (E)-ionone (1) [lo]. The reversible isomcrization 4 z? 5 is followed by the irreversible photoprocess 5 + 6 and the final transformation 6 + 7. Irradiation of iso-methyl-a, (E)-ionone (4) in acidic or basic solvents leads to a deep change in the type of products and gives the isomeric ketones 9 and 10 in high yields. A tentative mechanism for the photoisomcrization steps 5 -+ 6, 6 + 7 and 5 + 9 + 10 is proposed. Isomere Jonone mit einer zusatzlichen Methylgruppe in der tram-olefinischen Seitenkette sind seit inehr als 70 Jahren als Riechstoffe mit irisahnlicher Note und edelholzartigem Unterton bekannt und werden bis heute in der feinen Parfiimerie verwendet [6]. Die Uberfuhrung des wichtigsten Vertreters dieser Reihe, des Isomethyl-a, (E)-jonons (4) in die (Z)-Verbindung 5 wurde bereits vor mehreren Jahren von zwei Autoren der vorliegenden Veroffentlichung (G. 0. & J . I?.) in einer Patentschrift kurz beschrieben [7]. Die E + 2-Isomerisierung 4 + 5 zieht eine dramatische Anderung der Geruchseigenschaften nach sich. Das (2)-Isomer 5 besitzt eine kraftvolle und charakteristische Tabaknote von ambraartiger Nuance, die vorteilhafterweise von einem stark puderigen Geruchseffekt begleitet wird. Der blumige Duftcharakter und besonders der irisartige Geruch von 4 ist im (2)-Isomeren 5 uberhaupt nicht mehr vorhanden. Nachfolgend wird die Umwandlung 4 + 5 im einzelnen beschrieben und das weitere photochemische Verhalten des (2)-Ketons 5 geschildert.Den hier beschriebenen Untersuchungen geht nebst der erwahnten Arbeit von 1) 2) 3)79. Mitteilung in der ETHZ-Reihe Photochcmische Kcaktionen [l].

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Oxidation of secondary alcohols in diethyl ether with aqueous chromic acid. Convenient procedure for the preparation of ketones in high epimeric purity

Cited by 190 publications

References 2 publications

Enolboration 3. An Examination of the Effect of Variable Steric Requirements of R on the Stereoselective Enolboration of Ketones with R2BCl/Et3N. Bis(Bicyclo(2.2.2)Octyl)Chloroborane/Triethylamine - A New Reagent Which Achieves the Selective Generation of E Enolborinates from Representative Ketones

Enolboration 3. An Examination of the Effect of Variable Steric Requirements of R on the Stereoselective Enolboration of Ketones with R2BCl/Et3N. Bis(Bicyclo(2.2.2)Octyl)Chloroborane/Triethylamine - A New Reagent Which Achieves the Selective Generation of E Enolborinates from Representative Ketones

Electrolytic decarboxylation reactions. II. Syntheses of methyl dihydrojasmonate and methyl dl-jasmonate from 3-methoxycarbonyl-2-carboxynorbornane via anodic acetoxylation

Zur Photochemie des Iso‐methyl‐α, (E)‐jonons

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