Biogenetically Related Quinoline Alkaloids

Cinchona Group.—The relationship between conformation and antimalarial activity in the quinine series has been discussed.142 Apparently there is no intramolecular hydrogen-bond in the active alkaloids conversely, the inactive ones exhibit intramolecular hydrogen-bonding. 

Further reports on asymmetric synthesis in the presence of Cinchona alkaloids have been made.142 For example, hydrogenation of methyl pyruvate with a platinum-alumina catalyst containing quinine gives (+)-(/ )-methyl lactate in 87% optical yield.1426 Asymmetric induction with optical yields up to 36 and 26% has been observed in the Michael addition of thiols and nitro-alkanes to ct/ -unsaturated ketones in the presence of quaternary salts derived from the Cinchona alkaloids.142  

Camptothecin.—Hutchinson has contributed a detailed review of the chemistry, biosynthesis, and pharmacology of camptothecin and its derivatives.143 

In addition to several newly reported diterpenoid alkaloids, the structures of some forty alkaloids have been revised on the basis of recent work. The structures presented in this Report have been revised from those reported in the literature to reflect these recent corrections. The level of efforts directed toward the synthesis of diterpenoid alkaloids was substantially reduced this year, with only a description of the synthesis of napelline by Professor Wiesner s group appearing. No reports of new work on the Daphniphyllum diterpenoid alkaloids were available to our laboratories. 

The numbering systems used in this review follow the previous conventions for the aconitine, lycoctonine, atisine, and veatchine skeletons, as indicated in structures A, B, C, and D, respectively. 

Cinchona Group.—Details of Brown s partial synthesis54 1 of dihydro-meroquinene from secologanin have been published.126 

A further example of the use of copolymers of acrylonitrile and Cinchona alkaloids in asymmetric synthesis has been reported 127 thus these polymers catalyse the addition of benzyl mercaptan to w-nitrostyrene to give consistently an excess of the (+)-enantiomer of the adduct. 

Procedures for the separation of Cinchona alkaloids by h.p.l.c. have been described,128 and their separation by t.l.c. has been critically reviewed.129 

Camptothecin Group.—Camptothecin and 9-methoxycamptothecin are two of the major cytotoxic alkaloids of the wood and stem bark of Ervatamia hey-neana. li3° 

Details of the synthesis131 of desethyldesoxycamptothecin, by Walraven and Pandit, have been published.1316 

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The order of discussion in this chapter is the same as in previous volumes in this series, with the exception of the biogenetically related quinoline alkaloids, which are now placed at the end of the chapter. 

Despite the fact that quinine (66) and related alkaloids have quinoline skeleta biogenetically, they are indole alkaloids. Radioactivity from labeled loganin (11) and strictosid-ine (3) is incorporated into quinine. The indole nitrogen becomes the quinoline nitrogen (Fig. 34.19). Loganin (11), corynantheal (69), and probably cinchonamine (70) have been shown to be key intermediates in the biosynthesis of quinine (66), cinchonine (67), and cinchonidine (68) (Kapil and Brown, 1979). 

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