- A new synthetic approach to 7-hydroxynitidine
-
Benzo[c]phenanthridine alkaloid, 7-hydroxynitidine, was synthesized from readily available 2-benzyloxy-6-bromo-3,4-dimethoxybenzaldehyde 5 and napthylamine 6 using reductive amination followed by radical cyclization in eight steps. This method is highly e
- Ramani, Prasanna,Fontana, Gabriele
-
p. 5262 - 5264
(2008/12/21)
-
- Synthesis of NK109, an anticancer benzo[c]phenanthridine alkaloid
-
A total synthesis of NK109 (7-hydroxy-8-methoxy-5-methyl-2,3- methylenedioxybenzo[c]phenanthridinium hydrogensulfate dihydrate), an anticancer benzo[c]phenanthridine alkaloid, is reported. The primary structure of this compound was erroneously communicated in 1973 as fagaridine (from Fagara xanthoxyloides) which the 8-hydroxy regioisomer. NK109 has not yet been isolated from a natural source and therefore can only be obtained by synthesis. To study a wide variety of analogues, we decided to use a synthetic route via substituted benzylamine 5, which was obtained from the appropriate benzaldehyde ad naphthylamine units. The benzo[c]phenanthridine ring was conducted by radical cyclization with tri-n-octyltin hydride and 2,2'-azobis(2)-methylbutyronitrile], followed by oxidative aromatization with MnO2. The resulting benzo[c]phenanthridine 6 was successfully methylated with methyl 2-nitrobenzenesulfonate. After deprotection of the benzyl group and subsequent hydration, NK109 was obtained. All reactions were performed under normal conditions. Purification was achieved only by recrystallization to give an overall yield of 40%.
- Nakanishi, Takeshi,Suzuki, Masanobu,Mashiba, Akihiro,Ishikawa, Keizou,Yokotsuka, Takashi
-
p. 4235 - 4239
(2007/10/03)
-
- Methyl-Transfer Reactions. 6. Arenesulfonates as Nucleophiles and Leaving Groups. Methyl Trinitrobenzenesulfonate
-
The methyl-transfer reactions from several substituted methyl arenesulfonates to potassium benzenesulfonate in sulfolane have been studied with respect to both rates and equilibria.Because the reactions were followed by proton NMR of the methoxy group, only cases of methyl arenesulfonates with quite distinct methoxy chemical shifts from the unsubstituted ester could be studied, and this, in fact, required the use of ortho substituents.Hammett plots for these data were thus impossible, but a plot of log k+ vs. log K, although somewhat scattered, did allow an estimation of the rate of the identity reaction for the unsubstituted compound.These methyl arenesulfonates, as well as methyl iodide, were placed roughly on the scale of equilibrium methylating agents studied earlier in the same solvent.Methyl 2,4,6-trinitrobenzenesulfonate is a very reactive substance not compatible with sulfolane.It is soluble and stable only in thionyl chloride among a large number of solvents attempted and methylates a few weak nucleophiles more extensively than methyl trifluoromethanesulfonate.
- Lewis, Edward S.,Smith, Michael J.,Christie, J. Joseph
-
p. 2527 - 2531
(2007/10/02)
-