Zur Kenntnis der Triterpene. (46. Mitteilung). Ketoderivate und Oxyde der α‐ und β‐Amyrinreihe

Abstract

Bei der Oxydation des Acetats2) oder Benzoats3) des x-Amyrins mit Chromtrioxyd in kochender Eisessiglosung wird das der Doppelbindung benachbarte Methylen zu einer Ketogruppe oxydiert. Die 80 entstehenden Stoffe, Kcto-acetat bzw. Keto-benzoat, geben bei der Verseifung das gleiche B e t o -~-a m y r i n~)~) C,oI14,0,. Verseifung mit alkoholischer Lauge bereitete ,,,tI-Amyrin-oxyd", fur welches wir den Smp. 207--208° feststelltenl), ergab ein Maximum bei 2800 A (log E = 1,6). Es sollte also danach in diesen Verbindungen eine gesattigte Ketongruppe vorliegen, entstanden durch Um-I) Wir stellten diesen korr. Schmelzpunkt sowohl bei dem rnit Perskure wie auch bei dem mit Wasserstoffperoxyd bereiteten Praparat fest.

Ring-Size Effects in the Pinacol Rearrangement

“…In any of these sequences, the key intermediate is a dienone (2) (Chart I), prepared from /3-amyrin acetate in three steps involving consecutive oxidation by (i) hydrogen peroxide in acetic acid to give the saturated 12-ke-tone3-5; (ii) bromine to yield the conjugated 9(11)en-12-one5•6; and (ill) selenium dioxide7 with methyl group migration from C-14 to C-13. The structure of the dienone 2, which was first proposed by Jeger and Ruzicka,8 is now well established [2][3][4][5][6][7][8][9]. In current nomenclature,10 the dienone 2 is named 3/3-acetoxy-D-…”

Structure of Neo-β-amyrin1

“…The structure of the dienone 2, which was first proposed by Jeger and Ruzicka,8 is now well established. [2][3][4][5][6][7][8][9] In current nomenclature,10 the dienone 2 is named 3/3-acetoxy-Dfriedooleana-9(ll),14-dien-12-one; it has also been known variously as iso-/3-amyradienonyl acetate,7 oxoiso-/3-amyradienyl acetate,2 12-oxoisooleana-9(ll),-14-dien-3/3-yl acetate,11 and 12-oxotaraxera-9(ll),14dien-3/3-yl acetate.11 Reduction of the dienone 2 with lithium aluminum hydride2-6 or with sodium methoxide2 in methanol at ChabtI 200°y ielded a dienedioi, which was characterized as the diacetate and formulated as 3, with unassigned configuration at C-12. Treatment of this diacetate with hydrochloric acid resulted in deacetoxylation with formation of a cross-conjugated triene (neo-/3amyratrienyl acetate) which Spring and colleagues2 provisionally formulated as 4. The production of a cross-conjugated triene system from 3 necessitates a molecular rearrangement, for which this proposal, involving a migration of methyl group from C-13 to C-12, is the most obvious.…”

“…A distinction between the two most likely structures, 4 and 6, for the trienyl acetate was sought in examination of the n.m.r. spectrum.…”

THE OCCURRENCE OF α-AMYRIN AND URSOLIC ACID IN THE LEAVES OF Ilex paraguariensis

“…alpha-Amyrone. This product was prepared from the Ilex -amyrin according to the directions of Ruzicka, Muller, and Schellenberg (3). It melted at 123-125°, and it did not depress the melting point of an authentic sample of amyrone.…”