Jones oxidation ethers

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 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. 

The last synthesis to evolve which is due to Ito and his coworkers is interesting in that it relies on a stereospecific skeletal rearrangement of a bicyclo[2.2.2]octane system which in turn was prepared by Diels-Alder methodology (Scheme XLVIII) Heating of a toluene solution of cyclopentene 1,2-dicarboxylic anhydride and 4-methylcyclohexa-l,4-dienyl methyl ether in the presence of a catalytic quantity of p-toluenesulfonic acid afforded 589. Demethylation was followed by reduction and cyclization to sulfide 590. Desulfurization set the stage for peracid oxidation and arrival at 591. Chromatography of this intermediate on alumina induced isomerization to keto alcohol 592. Jones oxidation afforded diketone 593 which had earlier been transformed into gymnomitrol. 

Most silyl ethers, including the ubiquitous TBS ethers,22 resist Jones oxidation, with the exception of the very acid-sensitive TMS ethers.23... 

It is important to stress that, although MOM, TMS and THP ethers can be hydrolyzed under Jones oxidation, many cases are known in which this does not happen (Table 1.1.). 

In 1961, Brown348 described the oxidation of alcohols, using a two-phase system with aqueous chromic acid and diethyl ether. Brown s oxidation349 has a work-up, facilitated by the reluctance of ether to form emulsions with materials containing chromium, and although not as popular as Jones oxidation, it is used quite often. 

Asymmetric induction in cyclizution of a dienic acetal. Johnson et al reported a very high degree of asymmetric induction in the SnCl4-catalyzed cyclization of the iiL ctal I, derived from (—)-2,3-butanediol. Cyclization results in two axial ethers and two equatorial ethers cleavage and Jones oxidation converts these products into an nctuionc mixture consisting of 2a and 2b in the ratio 8 92. 

Reagents i, H2NOH,HCl-NaOAc-MeOH ii, NaBF CN-MeOH iii, (CH20)x-toluene, molecular sieves iv, FS03Me-ether v, L1AIH4-THF vi, Jones oxidation... 

Hydrolysis of alkylated products and carbonyl compound adducts derived from a-lithiated DHF and DHP with 2 M HC1 in THF at room temperature gave y- and 5-hydroxy ketones, respectively824,865 (Scheme 162). Jones oxidation generated keto acids866,887 and when the R substituent bears an hydroxy group, cyclization occurred in the presence of pyridinium tosylate (PPTS) in CH2C12 or HC1 in ether to provide spiroketals875,883,894,901. 

Jones reagent (1, 142-143).1 Phenols substituted by at least one alkyl group in the ortfio-position can be oxidized to / -quinones by a two-phase (ether/aqueous Cr03) Jones oxidation. Yields range from 30 to 85%, but the process is simple and more economical than use of Fremy s salt or thallium(III) nitrate. 

Radical addition of triphenylgermane to vinyl oxiranes proceeded in the presence of triethylborane to yield 4-triphenylgermyl-2-buten-l-ol derivatives in good yield. Iodo acetals, prepared by iodoetherification of vinyl ethers with the allylic alcohol, underwent radical cychzation to give 2-alkoxy-4-vinyltetrahydrofurans which were converted into 4-vinyltetrahydro-2-furanones by Jones oxidation (Scheme 11.22) [38]. 

Reductive removal of the halogen was achieved with tributyltin hydride and subsequent ozonolysis gave aldehyde 221. An aldol condensation of 221 with the trimethylsilyl enol ether of methyl propionate, followed by Jones oxidation... 

The free alcohol in 44 was protected as the silyl ether, and the less hindered C-3 acetate selectively hydrolysed and subjected to Jones oxidation (Scheme 20). The ketone was a-brominated to give 45 in 76 % yield, together with 14 % of the C-26 desilylated monobromide and 7 % of the 2,2-dibrominated product. 

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