Jones’ oxidation

The Collins/Sarett oxidation (chromium trioxide-pyridine complex), and Corey s PCC (pyridinium chlorochromate) and PDC (pyridinium dichromate) oxidations follow a similar pathway as the Jones oxidation (chromium trioxide and sulfuric acid in acetone). All these oxidants have a chromium (Vt), normally orange or yellow, which is reduced to Cr(lll), often greem 

By the Jones oxidation, the primary alcohols are oxidized to the corresponding aldehyde or carboxylic acids, whereas the secondary alcohols are oxidized to the corresponding ketones. 

Name Reactions A Collection of Detailed Mechanisms and Synthetic Applications, DOI 10.1007/978-3-319-03979-4 143, Springer International Publishing Switzerland 2014 

Bowden, K. Heilbron, I. M., Jones, E. R. H. Weedon, B. C. L. J. Chem. Soc. 1946, 39 5. Ewart R. H. (Tim) Jones worked with Ian M. Heilbron at Imperial College. Jones later succeeded Robert Robinson to become the prestigious Chair of Organic Chemistry at Manchester. The recipe for the Jones reagent 25 g CrOj, 25 mL cone H2SO and70mLH2O. 

Different from the Jones oxidation, the Collins oxidation, also known as the Collins-Sarett oxidation, converts primary alcohols to the corresponding aldehydes. Cr03 2Pyr is known as the Collins reagent. 

Andrieux, J. Bodo, B. Cunha, H. Deschamps-VaUet, C. Meyer-Dayan, M. Molho, D. Bull. Soc. Chim. Fr. 1976, 1975. 

Caamano, O. Fernandez, F. Garcia-Mera, X. Rodriguez-Borges, J. E. Tetrahedron Lett. 2000,41, 4123. 

Name Reactions, 4th ed., DOI 10.1007/978-3-642-01053-8 134, Springer-Verlag Berlin Heidelberg 2009 

Chromium trioxide is a strong oxidizing agent, and its use in organic synthesis had to overcome two problems  

In 1946, Jones discovered that secondary alcohols could be efficiently oxidized to ketones by pouring a solution of chromium trioxide in diluted sulfuric acid over a solution of the alcohol in acetone.13 This procedure, which has proved to be quite safe, allows a sufficient contact of the alcohol with chromium oxide derivatives for a reaction to take place. Jones oxidation marked the beginning of the highly successful saga of chromium-based oxidants. 

The action of sulfuric acid on chromium trioxide results in a number of equilibria, in which the major specie is chromic acid (see page 1). Thus, Jones conditions are often referred as chromic acid in acetone. 

It is also possible to prepare a chromic acid solution by treating sodium dichromate (Na2Cr207) or potassium dichromate (K C Ot) with sulfuric acid. Consequently, sodium14 and potassium15 dichromate can be used, instead of chromium trioxide, in Jones oxidations. 

Jones oxidation is carried out under very convenient experimental conditions with no need to employ a dry environment or an inert atmosphere. It is very useful for the oxidation of secondary alcohols, while it rarely succeeds in the transformation of primary alcohols into aldehydes due to its tendency to cause over-oxidation to carboxylic acids (see page 2). 

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ACOH/H2O, (3 1), 35°, 10 min, 100% yield. An IPDMS ether is more easily cleaved than a THP ether. It is not stable to Grignard or Wittig reactions, or to Jones oxidation. 

The TBDMS derivative of a /3-lactam nitrogen is reported to be stable to lithium diisopropylamide, citric acid, Jones oxidation, and BH3-diisopropylamine, but not to Pb(OAc)4 oxidation. 

An important task remaining is the stereocontrolled introduction of a methyl group at C-8. When a cold (-78 °C) solution of 14 in THF is treated successively with LDA and methyl iodide and then warmed to -45 °C, intermediate 24 admixed with minor amounts of the C-8 epimer is formed in a yield of 95 %. The action of LDA on 14 generates a lactone enolate which is alkylated on carbon in a diastereoselective fashion with methyl iodide to give 24. It is of no consequence that 24 is contaminated with small amounts of the unwanted C-8 epimer because hydrolysis of the mixture with lithium hydroxide affords, after Jones oxidation of the secondary alcohol, a single keto acid (13) in an overall yield of 80%. Apparently, the undesired diastereoisomer is epimerized to the desired one under the basic conditions of the saponification step. 

The acid (VII) formed in the Jones oxidation is readily separated from the nonacidic organic material by extraction of the ether layer with NaHC03 solution. The material not extracted by NaHC03 (neutral organics) was shown by NMR spectroscopy to consist of primarily the keto aldehyde VI. 

A group of arylalkylketones containing a basic substituent in the side chain shows CNS activities. Roletamide (190) is a hypnotic agent. It is prepared from 3,4,5-trimethoxybenzaldehyde (187) by addition of sodium acetylide (to give 188), followed by Jones oxidation of ethynylarylketone 189. Michael addition... 

Acid-catalyzed hydrolysis of the latter followed by Jones oxidation furnished racemic peshawarine (43) (Scheme 12). Simanek et al. (59) transformed the same amino acetal 47, obtained in optically active form from the Emde degradation of rhoeadine methiodide (48), to ( )-43, also by hydrolysis and oxidation. However, the optical activity was lost during hydrolysis (Scheme 12). 

The use of CrCb in aqueous acetone is usually called the Jones oxidation. 1) Jones oxidation rarely affects double bonds present in the molecule. 

The electrochemical oxidation is often more sensitive to the reaction conditions than to the substituents. Platinum electrodes are recommended for methoxylation and the equivalent acetoxylation procedures.290 In acetonitrile buffered by hydrogen carbonate ion, 3,4-diethylfuran affords the 2,5-dihydroxy-2,5-dihydro derivative (84%) and Jones oxidation readily leads to diethylmaleic anhydride in what is claimed to be the best general method for such conversions.291 In unbuffered methanol and under current density control, the oxidation of 2-methylfuran appears to eliminate the methyl group since the product is the acetal-ester 111 also obtained from methyl 2-furoate.292 If sodium acetate buffer is used, however, the methyl group is retained but oxidized in part to the aldehyde diacetate 112 in a... 

Treatment of progesterone with trifluoroacetic acid and triethylsilane in dichloromethane followed by saponification of the mixture of the trifluoroacetate ester intermediates of 5-/3-pregnane-3a,20/3-diol and 5-j6-pregnane-3a,20a-diol and Jones oxidation yields 5-/3-pregnanedione in 65% yield (Eq. 81).238... 

Diketones are reductively cyclized in a TFA-catalyzed reaction. The cycliza-tion of the cage structure shown in Eq. 236 illustrates this ring closure in the formation of an acetal of trifluoroacetaldehyde.409 The organosilane reduction of triketone 69 followed by Jones oxidation gives the cyclic ketoether in fair yield (Eq. 237).410... 

Namely, allyl alcohol is successively treated with diethylzinc, (R,R) dipropyl tartrate, and 4-methoxybenzohydroximinoyl chloride (163) to afford the enantiomeric isoxazoline alcohol 166, which under the Jones oxidation conditions affords the corresponding carboxylic acid derivative (167). Treatment of compound 167 with hydroxylamine-O-triflate followed by tri-fluoroacetic acid gives rise to the desired enantiomeric 165 in high excess enantiomeric yield. The synthesis of other isosteric analogues of 165 was reported in the same paper. None of the isosteric analogues exhibits LpxC inhibitory and antibacterial activities [103]. 

Jones oxidation coverted 46 in good yield to 6-oxosilicine (48, C19H22N202,... 

Another natural compound, 6-oxomethuenine (53, Cl9H20N202, MP >260°C, [a]D —15°), was obtained by Jones oxidation of 51 and gave the same UV spectrum as 48 in either acid or alkaline medium. 

The preparation of stannylthiazoles via ditin chemistry has not been widely utilized. In one case, the synthesis of 4-tributylstannylthiazole 43 started with selective halogen-metal exchange at C(2) by treating 2,4-dibromothiazole with n-BuLi [33]. Trapping the resulting 2-lithio-4-bromothiazole with propanal and subsequent Jones oxidation secured 4-bromothiazole 42. The Pd-catalyzed reaction of 42 with hexamethyldistannane in the presence of PdCWPhjP provided 4-tributylstannylthiazole 43. 

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