Indolo quinolines alkaloids

The yellow colored, sparcely soluble 5-ethyl-2-methyl-l l/f-pyrido[3,4-u] carbazolium 347 isolated from Aspidosperma gilbertii exists as a hydroxide after filtration of the corresponding iodide over basic aluminum oxide. A short synthesis was described (80CB3245). The Pyrido[3,4-a]carbazole ring system is present in the alkaloid AG-1, whereas Cryptolepine (348) possesses the indolo[3,2-b]quinoline moiety (65MI1). 

Caprio et al. (in 2000) reported the synthesis and inhibitory profile of a novel quinoline derivative against human telomerase [27]. The molecule bis-dimethylaminoethyl is a derivative of quindoline (10H-indolo[ 3,2-fo] quinoline) (for structure see Fig. 3), an alkaloid from the West African shrub Cryp-tolepis sanguinolenta, as reported by the authors [27]. The compound exhibits moderate cytotoxicity and inhibitory activity against telomerase. Utilizing molecular modelling technology, the authors hypothesized that the inhibitory... 

The authors have also extensively studied the indoloquinoline families of alkaloids related to cryptolepine (indolo[3,2-fo]quinoline 57), applying direct and long-range... 

Most of the compounds isolated from C. sanguinolenta are alkaloids and are analogs of indolo[3,2-f)]quinoline 11). The major alkaloidal component of the plant is cryptolepine (72). In addition to cryptolepine, comparatively small quantities of a number of related alkaloids have been isolated from the plant These include 11-hydroxycryptolepine, cryptoheptine, isociyptolepine, quindoline, bisciyptolepine, ciyptoquindoline, cryptolepicarboline, cryptospirolepine. Quindolinone, cryptotakienine, and cryptomisrine 11,13-16) (Figure 1). 

The analogous photocyclisation of enamides is well known and is of particular value in synthesis. Photocyclisation of the enamides (29) to the furopyridones (30), for example, has been used in the preparation of key intermediates for alkaloid synthesis. Similar approaches have been employed in the synthesis of corynanthe alkaloids ° and in the preparation of trans-hexahydro-indolo[43-ab]phenanthridines as selective dopamine agonists. The benzoylmethylenebenzothiazepines (31) can be converted in the same way into the B-homo-5-thiaprotoberberines (32). Enamide photocyclisation has also been employed in the syntheses of halo-benzofuro[2,3-c]quinolines,benzo[h][l]- and benzo[/j[1]-benzo-... 

Struct, unknown. Mol. formula not reported. Co-occurs with Cryptolepine and Quindoline (see 10/f-Indolo[3,2-6]quinoline, 1-00134). Could possibly be identical with the recently isolated Isocryptolepine. Alkaloid from roots of Cryptolepis sanguinolenta (Asclepiadaceae). Mp >300°. 

On the other hand a convenient combination of intramolecular aza-Wittig strategy and microwave technology for the preparation of the alkaloid, cryptotackieine, which has an indolo[2,3-h]quinoline core, has been described. Thus, treatment of 3-(o-azidophenyl) quinolin-2-one 145 with trimethylphosphine in nitrobenzene under microwave irradiation between 150-180 °C, after five-membered ring construction, afforded cryptotackieine (51) in 40% yield via 146 (Scheme 15.33). 

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