Notes 2665 into r values given above, assuming values of 2.73 for internal (solvent) chloroform peak, 5.35 for external water reference, and 8.77 for external cyclohexane reference, for the sake of convenience in comparing shift values. 4-Methylene-5,5-pentamethylene-3-phenyl-2-oxazolidinone (IVB) from 1-Ethynylcyclohexanol (IB).-To a solution of 3.5 g. of IB* *6 in 40 ml. of toluene, 3.7 g. of phenyl isocyanate was added and the mixture was heated under reflux for 4 hr. and then the solvent was removed under reduced pressure.The residue was diluted with about 40 ml. of petroleum ether (b.p. 30-60°) and this solution was extracted with 5% methanolic potassium hydroxide solution. The methanol layer was separated, neutralized with dilute hydrochloric acid, and extracted again with petroleum ether (b .p. 30-600). Concentrating this petroleum ether solution, followed by two recrystallizations of the residue from petroleum ether (b.p. 30-60°), gave 6.4 g. (88%) of the oxazolidinone, m.p. 167-167.5°.
Während sich das Dibenzoylmethan (Ia) mit dem Phenylhydrazin (II) in saurem Medium zu dem Pyrazol (III) cyclisiert, liefert das Brom‐Analoge (Ib) unter den gleichen Bedingungen das Flavon (IV), das beim Erhitzen mit Alkali′ in das Cumaran pyrazol (V) übergeht.
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