Cyclopentanols —

Show how each of the following compounds can be synthesized from cyclopentanol and any necessary organic or inorganic reagents In many cases the desired compound can be made from one prepared in an earlier part of the problem... 

Secondary alcohols, such as isopropyl alcohol, j -butyl alcohol, 2-pentanol, 3-pentanol, cyclopentanol, and cyclohexanol, have been autoxidized to hydroxyaLkyl hydroperoxides (1, X = OH R = H) (10,44). These autoxidations usually are carried out at ca 20°C with uv radiation in the presence of a photosensitizer, eg, benzophenone. a-Oxygen-substituted dialkyl peroxides (2, X = Y = OH and X = Y = OOH), also are formed and sometimes they are the exclusive products (10). 

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). 

The reaction involves nucleophilic substitution of for OR and addition of R MgX to the carbonyl group. With 1,4-dimagnesium compounds, esters are converted to cyclopentanols (40). Lactones react with Grignard reagents and give diols as products. 

The reaction of nitrous acid with the amino group of the /3-amino alcohol—e.g. 1-aminomethyl-cyclopentanol 1—leads to formation of the nitrosamine 4, from which, through protonation and subsequent loss of water, a diazonium ion species 5 is formed " —similar to a diazotization reaction ... 

In further modifications of these norprogestins, reaction of norethindrone with acetic anhydride in the presence of p-toluene-sulfonic acid, followed by hydrolysis of the first-formed enol acetate, affords norethindrone acetate (41). This in turn affords, on reaction with excess cyclopentanol in the presence of phosphorus pentoxide, the 3-cyclopentyl enol ether (42) the progestational component of Riglovic . Reduction of norethindrone affords the 3,17-diol. The 33-hydroxy compound is the desired product since reactions at 3 do not show nearly the stereoselectivity of those at 17 by virtue of the relative lack of stereo-directing proximate substituents, the formation of the desired isomer is engendered by use of a bulky reducing agent, lithium aluminum-tri-t-butoxide. Acetylation of the 33,173-diol iffords ethynodiol diacetate, one of the most potent oral proves tins (44). ... 

A solution of 1 g of the diacetate (III) in lOOcc of n-heptane containing 2.5 ccof cyclopentanol and 50 mg of p-toluenesulfonic acid is heated under reflux for 20 hours. After cooling, a few drops of pyridine are added and the solvent is eiiminated by evaporation under vacuum. The residue is taken up with methanol to give 3-cyclopentyl enolether of 17a-ethvnyl-19-nortes-tosterone ecetate which, after recrystalllzation from methanol, melts at 182°C to 1B4°C. 

How would you prepare the following substances from cyclopentanol More than one step may be required. 

The intensity of the m/z 31 ion is sufficient to suggest the presence of oxygen. Masses 44 and 57 are usually present, and an M - 18 peak is also detectable. Mass 44 usually suggests an aldehyde unbranched on the a-carbon, but this ion is also prominent in the mass spectra of cyclobutanol, cyclopentanol, cyclohexanol, and so forth. Mass 57 (C3H5O) is also fairly intense for C5 and larger cyclic alcohols. If an aldehyde is present, M - 1, M - 18, and M - 28 peaks are observed. 

Another example of a [2s+2sh-1c+1co] cycloaddition reaction was observed by Barluenga et al. in the sequential coupling reaction of a Fischer carbene complex, a ketone enolate and allylmagnesium bromide [120]. This reaction produces cyclopentanol derivatives in a [2S+2SH-1C] cycloaddition process when -substituted lithium enolates are used (see Sect. 3.1). However, the analogous reaction with /J-unsubstituted lithium enolates leads to the diastereoselective synthesis of 1,3,3,5-tetrasubstituted cyclohexane- 1,4-diols. The ring skeleton of these compounds combines the carbene ligand, the enolate framework, two carbons of the allyl unit and a carbonyl ligand. Overall, the process can be considered as a for-... 

Cyclopentane, methyl-, 55, 62 Cyclopentanol, p-toluenesulfonate [Ben-zenesulfonic acid, 4-methyl-, cyclo-... 

Benzenesulfnmc acid, 4-methyl-, cyclopentyl ester [Cyclopentanol, p-toluene-sulfonate], 55, 112... 

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