1 - cyclopentanol cyclopentanone

Some conversion into the anhydrovitamin (112) occurs during silica gel t.l.c. of retinyl palmitate in non-polar solvents. Some new colour reactions of vitamin A are reported to be better than the Carr-Price reaction. The kinetics and mechanism of acid-catalysed isomerization of retinyl acetate into the trans-retro-derivative (113) have been studied. Oppenauer oxidation of kitol (39) results in specific cyclopentanol-cyclopentanone oxidation. ... 

Cyclopentanethiol Cyclopentanol Cyclopentanone Cyclopentanone oxime Cyclop entene... 

Several procedures for making glutaric acid have been described in Organic Syntheses starting with trimethylene cyanide (28), methylene bis (malonic acid) (29), y-butyrolactone (30), and dihydropyran (31). Oxidation of cyclopentane with air at 140° and 2.7 MPa (400 psi) gives cyclopentanone and cyclopentanol, which when oxidized further with nitric acid at 65—75° gives mixtures of glutaric acid and succinic acid (32). 

Iwaki H, Y Hosegawa, S Wang, MM Kayser, PCK Lau (2002) Cloning and characterization of a gene cluster involved in cyclopentanol metabolism in Comamonas sp. strain NCIMB 9872 and biotransformations effected by Escherichia co/f-expressed cyclopentanone 1,2-monooxygenase. Appl Environ Microbiol 68 5671-5684. 

However, the reactions of mono substituted cyclopentanone sometimes becomes so much stereodirected that a mixture of cis and trans isomers is obtained. For example the reduction of 2-alkyl cyclopentanone by LiAlH4 gives a mixture of cis-trans isomeric alkyl cyclopentanols. 

Biological. Cyclopentane may be oxidized by microbes to cyclopentanol, which may oxidize to cyclopentanone (Dugan, 1972). 

Cyclopentanone is prepared by oxidation of cyclopentanol. Any one of a number of oxidizing agents would be suitable. These include PDC or PCC in CH2C12 or chromic acid (H2Cr04) generated from Na2Cr207 in aqueous sulfuric acid. 

However, with cyclppentanone only a 33% yield of cyclopentanol was obtained, the remainder of the material probably having undergone the above-mentioned condensation.6 As no appreciable condensation of this type occurs if dilute solution (approximately 0.05 molar) is used,10 it seems possible that dilution may improve the yields with particularly sensitive ketones such as cyclopentanone. 

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