Alkaloids hemiterpenoid

Non-hemiterpenoid Quinolines.—A re-examination of the alkaloids of Haplophyllum dubium resulted in the isolation of two members of the 2-aryl-4-quinolone group, i.e. graveoline (2 R = Me) and the new alkaloid norgraveoline (2 R = H).5 A new bacterial pseudan (3) has been obtained from Pseudomonas aeruginosa.8... 

Non-hemiterpenoid Quinolines.—New sources of the simple quinolines 4-methoxy-l-methyl-2-quinolone and its 8-methoxy-derivative (folimine) have been reported the former was isolated from Myrtopsis sellingii9 and from Zanthoxylum cuspidatum,16 and folimine was shown to be a constituent of Haplophyllum perforatum.5 The latter species also contains foliosidine (9), previously isolated from H. foliosum. The micro-organism Pseudomonas aertiginosa has been shown to contain 2-(hept-l-enyl)-4-quinolone (12).10 The structure of the alkaloid was established by n.m.r. and mass spectroscopy and by its synthesis from aniline and the j3-keto-ester Me(CH2)4CH=CHC0CH2C02Me. 

Carbon-13 N.M.R. Spectroscopy.—A study of the, 3C n.m.r. spectra of twenty-five hemiterpenoid quinoline alkaloids and related prenylquinolines, including C-, 0-, and A-prenyl-quinoline and -quinolone derivatives, hydroxyisopropyldihydro-furoquinolinones, hydroxydimethyldihydropyranoquinolinones, and furoquino-lines, has been carried out 6 only isolated examples were reported previously.7,8... 

Several reviews have appeared, on such topics as steroid and terpenoid biogenesis, hemiterpenoid alkaloids,indole alkaloids (monoterpenoids), ophiobolins (sesterterpenoids), sterols in Digitalis, oestrogens, plant tri-terpenoids, and carotenoids. ... 

Prenylquinoline Alkaloids.—A large number of alkaloids have already been separated from Ptelea trifoliata, including the hemiterpenoids with terminal double bonds that are characteristic of this species (cf. Vols. 1—3, 5, and 6). Two groups have now continued the investigation of the tertiary bases and quaternary salts of P. trifoliata. 

Ergot Alkaloids.—The hemiterpenoid unit of the ergot alkaloids is interesting in that, as expected, only one carbon atom is labelled by [2- C]mevalonic acid [marked by in formulae (14)—(17)] but the stereochemistry of this atom changes. Extensive studies by Floss etalf indicate that chanoclavine I (14) is converted into elymoclavine (17) via the aldehyde (15) and possibly via agroclavine (16) (however, see ref. 36a). This process involves two isomerisations about the isolated double bond. In dimethyl allyl pyrophosphate (5) the trans-methyl is labelled by... 

Prenylquinolinones and Hemiterpenoid Tricyclic Alkaloids.-3-Prenylquinolinones are well-known constituents of rutaceous plants and are biosynthetic and synthetic precursors of hemiter-penoid quinoline alkaloids all aspects of their chemistry feature... 

Non-hemiterpenoid Quinolines.—The three non-hemiterpenoid quinoline alkaloids reported this year are all 3-metho iyquinoline derivatives. Furoquinoline alkaloids had been isolated previously from Chloroxylon swietenia (East Indian satin wood), but now two new alkaloids, swietenidins A and B, have been obtained from the bark. Spectroscopic studies of swietenidin A and its monomethyl ether, and comparison of the data with those of the known 8-methoxy-iV-methyl-2-quinolone lunacridine, indicated that the alkaloid was the... 

Ptelea trifoliata is the only known source of hemiterpenoid quinoline alkaloids containing terminal double bonds, and nine compounds of this type have been isolated cf. Vols. 1—3, 5, and 7) the synthesis of two members of the group, O-methylptelefolonium iodide (26) and ptelefolone (29), has now been reported (Scheme 4). The 3-prenyl-4-methoxy-2-quinolone (24) was prepared by standard procedures and was converted with a peroxy-acid into a mixture of the dihydropyrano-quinolone (25) and the dihydrofuro-quinolone (27), Treatment of the latter with thionyl chloride and pyridine resulted in regiospecific elimination to give a terminal olefin, which afforded O-methylptelefolonium iodide (26). Successive reaction of the N-methyl-4-quinolone (28) cf. Vol. 7) with triphenyl phosphite dichloride and with pyridine resulted in an efficient synthesis of ptelefolone (29). 

The alkaloids of this chapter are classified according to the classification of terpenoids, namely hemiterpenoid alkaloids (alkaloids with a C5 unit), monoterpenoid alkaloids (alkaloids with a Cjo unit), sesquiterpenoid alkaloids (alkaloids with a C15 unit), diterpenoid alkaloids (alkaloids with a C20... 

Should all plant anthraquinones and their derivatives prove to arise by the same route as the anthraquinones of Ruhia tinctoruniy it follows that the medicinally employed purgative properties residing in various anthrone glycosides [119], Hke the adrenergic properties of the ergot alkaloids must now be considered as biological properties of hemiterpenoid derivatives. 

Neville CF, Grundon MF, Ramachandran VN, Reisch G, Reisch J (1991) Quinoline alkaloids. Part 28. The biosynthesis of fruoquinolines and other hemiterpenoids in Ptelea trifoliata. J Chem Soc Perkin Trans 1 2261-2268... 

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