Structure and configuration of tavimolidin
From the roots ofPeucedanum mogoltavicum Korov. have been isolated tadzhiferin, farnesiferol B, 5-methoxy-3,4-methylenedioxypropiophenone, and a new terpenoid coumarin — tavimolidin. The structure and absolute configuration of tavimolidin have been established on the basis of a study of its chemical and spectral characteristics. The passage from tavimolidin to feselol has confirmed the structure proposed previously for mogoltavinin, mogoltavin, and mogoltin and has established their absolute configurations.
Reduction of Steroid Ketones and other Carbonyl Compounds by Modified Wolff--Kishner Method
According to Dutcher and Wintersteiner2 the reduction of C3-steroid ketones by the Wow-Kishner method under usual conditions gives mainly the corresponding Cs-epimeric carbinols with small amounts of the expected Cs-methylenic products. In the case of the a,P-unsaturated ketone, cholestenone, the reduction follows a still more complex course. In addition to the epimeric unsaturated carbinols and a small amount of the normal product, A4-cholestene, the saturated carbinols, a-coprosterol and P-cholestanol have also been isolated. The authors stated that the abnormal reduction can be explained by the assumption that the hydrazone or semicarbazone is partially hydrolyzed to free ketone, which is then reduced by sodium alcoholate to give the secondary alcohol. These possibilities are, however, eliminated by the modified WolffKishner r e d ~ c t i o n , ~ , ~ in which the water is evaporated during the heating period. Moreover, the excess of hydrazine hydrate used in this reaction should keep the concentration of the regenerated ketone a t a low level.2 In fact all the C3-steroid ketones so far investigated gave the normal C3-methylenic compounds by the modified Wolff-Kish20-diketopregnane (I) gave a reduced product melting a t 152-153' in which one of the two keto groups is unattacked. In view of the fact that the 20-keto compounds, such as A5-pregnen-3 (P)-ol20-one (IV) and its hydrogenation product, allopregnan-3(P)-ol-20-one (VI) can be transferred to A5-pregnan-3 (P)-ol (V) and 3,P-hydroxyallo-pregnane (VII), respectively, the reduced product from I may be formulated as 3,a-hydroxy-1 l-ketopreg-
Sterol metabolism. XLI. Cholesterol A-ring autoxidations
Abstract Chromatographic and spectral evidence is adduced for the presence of cholest-5-en-3-one, cholest-4-en-3-one, and cholest-4-ene-3,6-dione in samples of cholesterol aged naturally in air or subjected to irradiation in air by 60 Co gamma radiation. These findings establish an additional mode of air oxidation of cholesterol to A-ring 3-ketones. Moreover, the oxidation by air of cholest-5-en-3-one induced by 60 Co gamma radiation yielded cholest-4-en-3-one, cholest-4-ene-3,6-dione, and the epimeric 3-oxocholest-4-ene-6-hydroperoxides. Cholest-4-en-3-one was not altered by irradiation in air, nor was cholesterol isomerized to cholest-4-en-3β-ol upon irradiation. From these observations it is deduced that the radiation-induced A-ring dehydrogenation of cholesterol yields initially cholest-5-en-3-one which upon isomerization yields cholest-4-en-3-one not further oxidized and which by a second oxidation yields the epimeric 3-oxocholest-4-ene-6-hydroperoxides which decompose to cholest-4-ene-3,6-dione.