2- cyclobutanol cyclobutanone

Cyclobutanamine Cyclobutane Cyclobutanecarbonitrile Cyclobutanecarboxylic acid 1,1-Cyclobutanedicarboxylic acid Cyclobutanol Cyclobutanone Cyclobutene... 

Cyclobutanol entsteht in guter Ausbeute bei der Reduktion von Cyclobutanon mit Lithiumaluminiumhydrid 171). Cis- und trans-Cyclobutandiol-1.2 gewinnt man nach Criegee und Weldes 70)... 

Functional Group Interconversions Including Functionalization 5.2.4.1, Formation of One C—H Bond Reduction of Cyclobutanone to Cyclobutanol... 

All of the usual chromium-based oxidation reagents that have been used for the oxidation of cyclobutanols to cyclobutanones, for example, chromium(VI) oxide (Jones reagent),302 pyri-dinium chlorochromate,304 pyridinium dichromate,307 and chromium(YI) oxide/pyridine (Collins),303 are reported to do so without any serious problems. Alternatively, tetrapropylam-monium perruthenate in the presence of A-methylmorpholine A -oxide. oxalyl chloride in the presence of triethylamine in dimethyl sulfoxide (Swern),158,309,310 or phenyl dichlorophos-phate in the presence of triethylamine and dimethyl sulfoxide in dichloromethane (Pfitzner-Moffatt),308 can be used. The Pfitzner-Moffatt oxidation procedure is found to be more convenient than the Swern oxidation procedure, especially with respect to the strict temperature control that is necessary to achieve good yields in the latter, e.g. oxidation of 1 to give 2.308... 

Examples of the oxidation of cyclobutanols to cyclobutanones are given in Table 14. 

A similar example is the ring expansion of cyclobutanone via l-tris(methylsulfanyl)methyl-cyclobutanol (6) to 2,2-bis(methylsulfanyl)cyclopentanone (7).43 The use of Af,A-diisopropyl-ethylamine is unneccessary in this reaction as the hydroxy group has already been deprotonated with butyllithium. Further examples of this type of reaction can be found in refs 43 and 44. 

The same mode of migration is found if the rc-bond needed for rearrangement is part of an aryl ring in the 2-position. Usually only the substituted C3 of cyclobutanones (Table 5)71 74,140 or cyclobutanols (Table 6)75 migrates on treatment with trifluoroaeetic acid,73 methanesulfonic acid,71 trifluoromethanesulfonie acid, 140/ -toluenesulfonic acid,74 phosphorus pentoxide,71-74 and tin(IV) chloride,72 generally with diethyl ether or benzene as the solvent. 

In recent years, inorganic hydrides such as lithium aluminum hydride, LiAlH4, and sodium borohydride, NaBH4, have become extremely important as reducing agents of carbonyl compounds. These reagents have considerable utility, especially with sensitive and expensive carbonyl compounds. The reduction of cyclobutanone to cyclobutanol is a good example, and you will... 

Intermolecular coupling of ketones and alkenes, promoted by SmH, occurs with excellent stereochemical control. In one such reaction, samarium(II) iodide has been used to prepare cyclobutanones and cyclobutanols from chiral, 6-oxohex-2-enoates (equation 137)520. The reaction is performed in THF in the presence of HMPT and occurs in good yield with excellent stereocontrol. If appropriately located carbonyl and alkene moieties are present in a molecule, then Sml2-HMPT can be used to form cyclooctanols by a radical cyclization process in some cases there is a reasonable degree of diastereoselectivity (equation 138)521,522. 

Whatever the case, the formation of the cyclooctenone 320 from the cyclobutanone 317 constituted the first example of a one-step C4 — C8 ring expansion. In the same way, the spirocyclobutanone 266 63,73), was treated with vinylmagnesium bromide to generate a mixture of the diastereomeric cyclobutanols 322 and 323 in 78% yield (ratio 21/79). Each diastereomer, separated by HPLC, individually subjected to KH in THF at room temperature, rearranged cleanly to bicyclo[5.3. l]undec-l(l l)-en-4-one in 80% yield, Eq. (87)161>. 

Ruvn—>RuIV) the fact that it selectively oxidizes cyclobutanol to cyclobutanone and ferf-Bu(Ph)CHOH to the corresponding ketone, militates against free-radical intermediates and is consistent with a heterolytic, two-electron oxidation [103, 104]. Presumably, the key step involved /1-hydride elimination from a high-valent, for example, alkoxyruthenium(VII), intermediate followed by reoxidation of the lower-valent ruthenium by dioxygen. However, as shown in Fig. 18, if this involved the Ru(VII)/Ru( V) couple the reoxidation would require the close proximity of two ruthenium centres, which would seem unlikely in a polymer-supported catalyst. A plausible alternative, which can occur at an isolated ruthenium centre, involves the oxidation of a second molecule of alcohol, resulting in the reduction of ruthenium(V) to ruthenium(III), followed by reoxidation of the latter to ruthenium(VII) by dioxygen (Fig. 18). 

The reaction of the silyloxypyrroles 47 possessing a chiral substituent at the nitrogen atom, with cyclobutanone in the presence of a Lewis acid, followed by an acid induced ring expansion of the cyclobutanol intermediate 48, offers an asymmetric route to the l-azaspiro[4.4]nonanes 49 in good diastereoisomeric excess <02SL1629>. In this context it might also be interesting to... 

Gas-liquid chromatography [1/8 in. x 6 ft, 10% diethylene glycol succinate (LAC-728) column, 70°C] of cyclobutanone (99.2% pure) revealed the presence of small amounts of methylene chloride (0.6%) and cyclobutanol (0.2%). No cleavage product, 4-hy-droxybutyraldehyde, was found. The traces of water, detected by NMR spectroscopy using CD3COCD3 as a solvent, can be removed by drying over molecular sieves. 

If the preparation of cyclobutanone from cyclopropylcarbinol is carried out in two steps, with cyclobutanol isolated first, somewhat higher yields can be achieved (70-80% based on cyclobutanol, 45-50% overall yield, purity 98-99%). 

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