119(P-54) Pd(OAc)_2-DPPP-^nBu_3Pより製した新規パラジウム反応剤によるbiaryl閉環反応を用いたbenzo[c]phenanthridine alkaloid類の合成研究(ポスター発表の部)
スポンサーリンク
概要
- 論文の詳細を見る
Fully aromatized benzo[c]phenanthridine alkaloids have attracted considerable attention because of a variety of pharmacological and biological activities. It has been reported that, among these alkaloids, chelerythrine (1) mediates a variety of biological responses, and isofagaridine (3) inhibits DNA topoisomerase I. Nitidine (2) was found to show a storong antileukemic activity. Extensive efforts have been directed toward the development of a convinient method for synthesizing benzo[c]phenanthridine alkaloids. However, the reported methods involved several disadvantages such as numerous steps, low total yield and/or absence of generality. Therefore, we developed a versatile method of synthesizing these alkaloids. The internal cross coupling reaction with Pd catalyst has been utilized for the synthesis of condensed aromatic compounds, and we have recently succeeded in a convenient synthesis of oxychelerythrine (11), including a biaryl coupling reaction of halo-amides (9, 10, X=I or Br), by Pd(OAc)_2, PPh_3 or P(o-tol)_3 [tris(2-methylphenyl)-phosphine] and Ag_2CO_3 in DMF under reflux. Subsequently. we invesegated a biaryl cyclization reaction of amide possessing a triflate group instead of a halogen group as a leaving group and found a novel palladium reagent system prepared from Pd(OAc)_2, DPPP [1,3-bis(diphenylphosphino)propane] and ^nBu_3P for this purpose. And we were succeeded in synthesizing chelerythrine (1) and nitidine (2) by this novel reagent system. Moreover. this method was proven to be effective not only for the triflate group but also halogen group as a leaving group. To investigate the generality of this method, we applied it to synthesis of the tertiary bases, 12-methoxydihydrochelerythrine (4) and norchelerythrine (5). We found that the cyclization reaction assisted by palladium proceeded smoothly in high yield when tertiary amide were used as a substrate.
- 天然有機化合物討論会の論文
- 2000-10-01
著者
関連論文
- 48(P-15) ヒカゲノカズラ科植物Lycopodium serratum含有アルカロイド類に関する化学的研究(ポスター発表の部)
- 21 Graphislactone類および関連化合物の合成(口頭発表の部)
- 119(P-54) Pd(OAc)_2-DPPP-^nBu_3Pより製した新規パラジウム反応剤によるbiaryl閉環反応を用いたbenzo[c]phenanthridine alkaloid類の合成研究(ポスター発表の部)