Jerome L. Moniot

Flavone C-glycosides from Coronilla varia

Abstract One new and 5 known flavone C -glycosides were isolated from leaves and stems of Coronilla varia . The new compound was shown to be isoorientin 2″- O -rhamnoside. The known compounds were isovitexin, isoorientin, isovitexin 4′- O -glucoside, isoorientin 4′- O -glucoside, and isoorientin 7- O -glucoside.

A biogenetically patterned conversion of magnoflorine into taspine

Ozonation of diacetylmagnoflorine methine followed by oxidation and lactonization affords taspine.

The Simple Isoquinolines

The chemistry, synthesis, and biogenesis of peyote, Lophophora williamsii (Lemaire) Coult., and other cactus alkaloids have been thoroughly reviewed.1–5

The Homoaporphines and Homoproaporphines

Several homoaporphines and reduced homoproaporphines have recently been isolated from members of the Liliaceae, mostly by the Russian school. The assigned structures are reproduced below. However, in the case of the reduced proaporphines, the data available are fragmentary, and some of the stereochemical assignments still remain to be made or to be confirmed.

Eupolauridine: A 1,6-Diazafluoranthene

Occurrence: Annonaceae and Eupomatiaceae (These two families are closely related botanically.)

Emetine and Related Bases

No new alkaloids in this series have been isolated. However, the structure of ankorine has been revised1 and that of alangiside has been established with certainty.2

The N-Benzyltetrahydroisoquinolines

No new N-benzyltetrahydroisoquinolines have been isolated from natural sources in recent years. However, the structure of corgoine has been confirmed by three syntheses. The first involves reduction of the N-benzyl quaternary salt derived from isoquinoline l,1 whereas the second approach utilizes the Pictet-Spengler reaction to cyclize the substituted phenethylamine 2 (see Scheme 31.1).2

The 3-Arylisoquinolines

In this small group of alkaloids, the 3-arylisoquinolines, as in the benzo-phenanthridines (see Sec. 21.1) to which they are clearly related, the nitrogen heterocycle can be either fully aromatic or saturated. All three members of the 3-arylisoquinolines have been isolated from Corydalis incisa, a plant also known to produce benzophenanthridines.

Cherylline: A 4-Arylisoquinoline

Cherylline has been synthesized anew by a route which calls for a quinone methide cyclization in the final step. The methoxy bromide 2 was condensed with the benzylamine 1, and concentrated hydrochloric acid cyclized the adduct to cherylline.1

The Azafluoranthenes and Tropoloisoquinolines

Azafluoranthene bases have been found to date only within the family Menisper-maceae. A recent addition to this small group of optically inactive alkaloids is norrufescine, C18H15NO4, whose PMR spectrum is close to that of the known base rufescine. Diazomethane O-methylation of norrufescine generated rufescine. The location of the phenolic function in ring D was confirmed by a positive coupling reaction of the alkaloid with p-nitrobenzenediazonium chloride.1