Synthesis of NK109, an Anticancer Benzo[c]phenanthridine Alkaloid
摘要:
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 is 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 and naphthylamine units. The benzo[c]phenanthridine ring was constructed 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%.
A novel phenanthridinium derivative represented by general formula (A):
wherein R1 is a substituted or unsubstituted lower aliphatic hydrocarbon group; R is an aliphatic hydrocarbon chain having 2 to 6 carbon atoms which may optionally be substituted with a substituent selected from the group consisting of a lower alkyl group, a halogen and a hydroxy group; each of Y and Z independently represents a hydrogen, a hydroxy or a lower alkoxy group; or Y and Z are combined together to form methylenedioxy or a phenyl ring;
and, X− is an acid residue or a hydrogen acid residue, exhibits an antitumor activity and has resistance to chemical reduction as well as biological metabolic reactions and is thus advantageous for use as a medicine.
Transmetallations between aryltrialkyltins and borane: synthesis of arylboronic acids and organotin hydrides
作者:M Faraoni
DOI:10.1016/s0022-328x(00)00536-2
日期:2000.11.3
Aryltrialkyltin compounds react with borane in THF to give mixtures of trialkyltin hydrides and arylboranes, which on hydrolysis give arylboronic acid in high yields. The arylboronic acids are easily separated and obtained free of organotins. (C) 2000 Elsevier Science B.V. All rights reserved.