Cyclobutanols oxidative cleavage

The cyclobutanols (458) underwent oxidative cleavage with chromic acid to provide diketones (459) (Table 19)157). 

Oxidative cleavage of cyclopropanes has been studied mostly with lead(IV), thaIlium(III) and chromium(Vl) reagents. - The oxidative cleavage of cyclobutanols has been explored mainly with chro mium(VI) reagents, although other oxidants have been studied. ... 

Cyclobutanols oxidize with ring cleavage to 4-hydroxy ketones, 4-hydroxy acids, or 1,4-diones under the influence of chromium(Vl) reagents (Scheme 11). The first formed product is a 4-hydroxycarbonyl compound (31) which exists as the five-membered ring hemiacetal (32). This form will persist in the absence of excess reagent under nonforcing conditions otherwise further oxidation takes place to give a... 

Phenyliodine diacetate-mediated oxidative cleavage of cyclobutanols leads to the formation of y-hydroxy ketones, y-Substituted y-hydroxy ketones were obtained from 2-substituted cyclobutanols through regioselective C-C bond cleavage. ... 

In extensions of some earlier studies, Wada et al. have shown that a useful method of cyclopentane annelation is by rearrangement of protonated cyclopropyl ketones, to y-hydroxy-ketones, viz. (51), followed by oxidation to 1,4-diones and base-catalysed cyclization (Scheme 16). Both oxidation of a-allyl-ketones, using PdCl2-CuCl in DMF under an oxygen atmosphere, and the oxidative cleavage of t-cyclobutanols using Jones reagent provide alternative new approaches to... 

Cyclopropanol (Schaafsma et al., 1966) and cyclobutanol (Meyer and Rocek, 1972) undergo rapid oxidative cleavage, due to the release of the strain energy of the aliphatic ring. Chain opening is a typical reaction of strained cycloalkanols in presence of one-electron oxidants. A mixture of reaction products is formed, and the actual composition of the reaction... 

The mechanism of the oxidation of tertiary cyclobutanols with Jones reagent is believed to involve the intermediate lactols (Eq. (18)) and the cleavage of the lactol to ketol and its subsequent oxidation to diketone when R1 = H157). 

Various oxidation conditions which could promote the ring cleavage of cyclobutanols have been briefly reviewed 158). This work was extended to the cyclo-... 

The photochemistry of isomesityl oxide is rather interesting in that cyclobutanol formation and type I cleavage proceed with a fair quantum yield.361 The efficiency of the process may indicate that energy transfer to the double bond is not favored.361 However, it is likely that most of the photoreaction proceeds from an excited singlet. 

The photochemical addition of cyclic 1,3-diones such as dimedone, 1,3-cylohexandione 62, or their respective silyl enol ethers leads to the formation of two fused furanylfullerenes, (1) achiral 63 and (2) chiral 64 [244], The latter having an unusual bis-[6,5] closed structure. In the initial step of this reaction, [2 + 2] photocycloaddition across a [6,6] bond to form cyclobutanols or the corresponding TMS ethers is involved (Scheme 26). Oxidation with 02 yields in the formation of the radical 65a. Cleavage to 66a followed by cyclization gives furanyl radical 67a. H abstraction by 102 or a peroxy radical finally leads to product 63. In competition, formation of fullerene triplets by absorption of a... 

Solid supported isoxazolines 40 were prepared starting from a sulfmate-functionalised resin 38. Oxidation of the resin linked cyclobutanols 40, with concomitant cleavage of the sulfone linker, produced isoxazolinocyclobutenones 41 in 34-38% overall yield (4 steps) <02OL741>. A five-step solid phase synthesis of isoxazolino-pyrrole-2-carboxylates that employing the same traceless sulfone linker strategy has also been reported <02JOC6564>. 

The chromic acid oxidation of cyclobutanol may be complicated by ring-cleavage reactions mediated by lower oxidation states of chromium, as discussed in a previous Report, but these side-reactions can be suppressed and cyclobutanone obtained in good yield by the addition of oxalic acid. ... 

Chromic acid oxidation of 1-substituted cycloalkanols (434 m = 0,1,..n = 1,2, 3. ..) proceeds with ring-cleavage, giving keto-acids. Lead tetra-acetate oxidation of the cyclobutanol (435) has been reported to take an unusual course, giving in addition to the expected y-hydroxy-ketone (436) the new compound (437), whose structure was confirmed by X-ray analysis. 

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