Indoles pyrrolizidine

With the exception of the recent isolation (2) of the unusual indole-pyrrolizidine base, peduncularine, from Aristotelia peduncularis (Labill.) Hook.f., alkaloids have not yet been reported from other genera of the Elaeocarpaceae. 

Peduncularine was obtained from Aristotelia peduncularis (Labill.) Hook f. by Bick et al who postulated an indole-pyrrolizidine structure (44) for this alkaloid. On the basis of more extensive spectroscopic studies (including C n.m.r. spectroscopic data) and degradative work, a revised structure (45) has been proposed by Ros et al which shows that peduncularine belongs to the class of monoterpene indole alkaloids, and has no connection with pyrrolizidine alkaloids. 

By employing intramolecular 1,3-dipolar cycloadditions, syntheses of pyrrolo-, pyrido[l,2-a]indol (140),a pyrrolizidine and indolizidine (140b) derivatives have been reported (Scheme 2.216). 

Aromatic azapentalenes have not been found naturally, though an imidazo[4,5-d]imidazole derivative has been implicated in the prebiotic synthesis of purines130 74 (see also Section III,A,l,d). Saturated derivatives occur fairly widely the Senecio alkaloids contain the reduced pyrrolol l,2-a]pyrrole (pyrrolizidine) skeleton,487 and the alkaloid withasomnine is a derivative of pyrrolo[ l,2-6]pyrazole.374,488 The mitomycin antibiotics mentioned earlier in this review (Sections III,B,l,f and III,B,5) contain the pyrrolol l,2-a]indole ring,166,331 and the recently reported fungal metabolite sporidesmin is a saturated derivative of pyrrolo[2,3-6]indole.489... 

Alkaloids are basic plant natural products that typically have a nitrogen atom as part of a heterocyclic ring system and indeed are classified on this basis. Thus major classes of alkaloids are based on indole, isoquinoline, pyrrolidine, piperidine, pyrrolizidine, quinoline, tropane, quinolizidine or other heterocyclic ring systems. Other alkaloids are basic monoterpenoid, sesquiterpenoid, diterpenoid, steroid, purine, pyrimidine or peptide entities. Some of these compounds are exceptionally toxic [1,6, 7-12]. 

Several (A/-alkenyl)iodoacetamides undergo cyclization when they are reacted with tetrakis(triphe-nylphosphine)palladium(O). The highest yields (which are generally only moderate) are obtained in DMF solution with 1,8-dimethylaminonaphthalene (Proton Sponge) to take up the hydrogen iodide formed. This reaction has been used to prepare piperidones, oxindoles, indolizidines, quinolizidines, pyrrolidines, indoles, quinolines53 and pyrrolizidines (equation 18).54... 

Over seven-hundred references are concerned with the isolation and chemistry of alkaloids, and approximately one-third of these are devoted to synthesis and biosynthesis. It is perhaps in these areas that the most notable research is to be found. Although it is probably invidious to attempt the exercise, a personal selection of highlights would include new results on the biosynthesis of quinoliz-idine alkaloids (p. 4), the first synthesis of an eleven-membered macrocyclic pyrrolizidine diester (p. 49), the synthesis of Poranthera alkaloids (p. 68), and, in the indole field, the synthesis of tryptoquivalines G and L (p. 152), of a chiral intermediate in the construction of heteroyohimbine alkaloids (p. 167), and of a catharanthine intermediate, using palladium catalysts (p. 186). 

Depending on the reaction medium some cyclic alkaloids behave as ring enlarged or as ring contracted compounds. In Scheme VIII/19 indole alkaloids vomicine and perivine, the isoquinoline alkaloid protopine, and pyrrolizidines are given with their ring contracted forms. 

Senecio alkaloids, see Pyrrolizidine alkaloids Simple indole alkaloids, 10, 491 (1967)... 

Keywords alkaloid biosynthesis alkaloid genes nicotine tropane alkaloids pyrrolizidine alkaloids benzylisoquinoline alkaloids monoterpene indole alkaloids ergot alkaloids acridone alkaloids purine alkaloids taxol betalains... 

Gercideae. (a) The occurrence of alkaloids. Key to branches leading to families that accumulate quinolizidines, pyrrolizidines (No. 1 see arrows) Erythrina (No. 3) indolizidines (No. 4) p-carbolines (No. 5) or simple indoles (No. 2) are marked. The rbcl sequences used (1400 bp) derived from Kass and Wink, 1997a,b Wink and Mohamed (2003). Trees were reconstructed with maximum parsimony. 

Encouraged by these results, we sought other aromatic acid ring systems for coupling to our pyrrolizidine scaffold. A series of indole-... 

Aside from histamine, pyrrolizidine, quinoline and indole alkaloids, annuloline... 

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