Diethyl Ether → 2-(7-Hydroxyheptyl)cyclopent-2-en-1-one

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

A mixture of 7-(2-tetrahydropyranyloxy)heptanal (22 g.) and 1-morpholinocyclopentene, i.e. the morpholine enamine of cyclopentanone, (21.4 g.) in benzene (25 ml.) was heated under reflux for 12 hours under nitrogen, and the water liberated was continuously removed with a Dean and Stark head. Benzene (10 ml.) and then, dropwise, 18% hydrochloric acid (28 ml.) were added and the mixture was stirred for 2 hours. The organic layer was separated and evaporated. Concentrated hydrochloric acid (72 ml.) and butanol (300 ml.) were added to the residue. The mixture was heated at 100° C. for 1 hour, and then the solution was concentrated to give an oil. Diethyl ether was added, and the ether solution was washed with aqueous sodium bicarbonate and then water, and dried over sodium sulphate. The solvent was evaporated and the residue was distilled under reduced pressure to give 2-(7-hydroxyheptyl)cyclopent-2-en-1-one (11.7 g.), b.p. 125°-170° C./0.15 mm.Hg, nD25 1.490, λmax 228 mμ (ethanol).

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