Pyrrolophenanthridine

Mdrour synthesized a series of indolo[2,l-a]isoquinolines and pyrrolophenanthridines via Heck cyclizations onto the C-2 and C-7 positions of indole, respectively [274], Two examples are shown. 

Pyrrolophenanthridines and Related Alkaloids Lycorine and Related Alkaloids Galanthamine and Related Alkaloids Crinine and Related Alkaloids Tazettine and Related Alkaloids... 

Aromatisation of the latter with dichlorodicyano 1,4-benzoquinone, however, proceeded in low yield to furnish the pyrrolophenanthridine derivative 163. Reduction of 163 with lithium aluminium hydride furnished 1 l-hydroxyanhydrolycorine (156) which on mesyiation... 

A definite picture of the biosynthesis of norpluviine (10), the key intermediate to the pyrrolophenanthridine, and the lycorenine-type alkaloids was derived from two sets of feeding experiments. 

The activity of 6-alkyl substituents is well shown by the ease with which 6-methyl- and 6-ethylphenanthridinium-5-enol betaines (215) (R = Me and Et) undergo cyclodehydration to pyrrolophenanthridines (238) (R = H or Me) on heating, since the first step presumably involves proton transfer from the a-carbon atom of the alkyl substituent.285... 

This method can be applied to the total synthesis of natural products. The lycorine alkaloids anhydrolycorinone and hippadine have a pyrrolo[3,2,l-de]phenanthridine framework and have been isolated from Amaryllidaceae plants [26]. Hippadine exhibits reversible inhibition of fertility in male rats. Diverse synthetic approaches to the pyrrolophenanthridine alkaloids have been developed because of their potent biological activities [27[. We applied the iron(O)-mediated arylamine cydization described above to a concise synthesis of anhydrolycorinone and hippadine (Scheme 15.7) [28]. 

The total synthesis of the pyrrolophenanthridine alkaloid, hippadine, was accomplished in the laboratory of T. Sakamoto. The last and key step of the synthetic sequence was the Stille-Kelly coupling of the A/-benzoylated indole precursor in 68% yield. 

A chloroacetylarylamine (90.9, n = I) may be converted into quinolin-2-one [2960] by treatment with the Vilsmeier reagent (review [1676]). A novel method of forming this ring was recently described as a stage in the synthesis of pyrrolophenanthridine alkaloids such as ungeremine. A C—C bond is formed by a radical mechanism of debromination by benzyl triethylammonium chloride... 

Moore s group has also exploited his methodology for the synthesis of a variety of 7V-heterocyclic quinones and hydroquinones such as piperidinoquinones 37, dihydrophenanthridinediols 38, benzophenanthridine 39, and assoanine 40, a member of a series of biologically active pyrrolophenanthridine alkaloids. ... 

An advantage of LPDE system compared with other typical Lewis acids is a wide range of functional group compatibility. Utilizing this advantage of LPDE system, efficient syntheses of complex organic molecules, such as proxiphomin [23], and pyrrolophenanthridine [24], were accomplished (Scheme 3.5 and 3.6). 

Applicalion of this methodology toward the synthesis of oxoassoanine (298) [108] and anhydrolycorin-7-one (299) was also carried out [109]. These compounds are members of the pyrrolophenanthridine class of alkaloids, which have... 

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