Tetrahydrofuran cyclopentanol

Reduction of unsaturated ketones to saturated alcohols is achieved by catalytic hydrogenation using a nickel catalyst [49], a copper chromite catalyst [50, 887] or by treatment with a nickel-aluminum alloy in sodium hydroxide [555]. If the double bond is conjugated, complete reduction can also be obtained with some hydrides. 2-Cyclopentenone was reduced to cyclopentanol in 83.5% yield with lithium aluminum hydride in tetrahydrofuran [764], with lithium tris tert-butoxy)aluminium hydride (88.8% yield) [764], and with sodium borohydride in ethanol at 78° (yield 100%) [764], Most frequently, however, only the carbonyl is reduced, especially with application of the inverse technique (p. 21). 

Cyclohexadienones, not unexpectedly, can been employed to obtain alkylphenolic systems. Thus a solution of the p-quinone methide depicted when slowly introduced in tetrahydrofuran solution over 2 hours into samarium(ll) iodide at 35°C followed by work-up with sodium bicarbonate solution gave a 67% yield of (E)-2-(3,5-dimethyl-4-hydroxyphenyl)cyclopentanol. The Smij was obtained by treating samarium during 1 hour with methylene diiodide in tetrahydrofuran at 0"C and reacting for a further hour (ref.9). 

Cycloalkanols. A mixnire of RMgX and Sml converts co-haloalkanoates into cycloalkanols. Thus, cyclopropanols are prepared very readily, while cyclopentanols and. > clohexanols are obtained in lower yields, but cyclobutanols cannot be made by this -lethod, since tetrahydrofuran derivatives are formed. 

---