STUDIES ON THE SYNTHESIS OF ANTITUMOR PYRROLOIMINOQUINONE MARINE ALKALOIDS

吡咯亚氨基醌类海洋生物碱因其潜在的抗肿瘤活性而备受关注。在这个研究项目中，我们开发了一种新的有效的方法来构建和功能化吡咯亚氨基醌的核，主要是基于定向锂化法，即1-三异丙基-6-甲氧基氨基在吲哚环的4-位通过直接锂化法氯化，然后与六氯乙烷反应。用常规方法将氯化葡萄胺转化为1-保护-6-甲氧基色胺衍生物。在芳烃的作用下，色胺被环化成关键的三环7-甲氧基-1，3，4，5-四氢吡咯并[4，3，2-去]喹啉类化合物。三环化合物在Fremy盐或Salcomine催化下氧化生成7-甲氧基吡咯亚氨基醌，再与氯化铵或酪胺盐酸盐(Tetrahedron，1998，54,8999)反应生成吡咯亚氨基醌海洋生物碱Makaluvamine A，D，1和K。然后，通过N-Boc直接锂化合成了1，3，4，5-四氢吡咯并[4，3，2-de]喹啉核的6-选择性官能化。用该方法首次全合成了一种新型的C-6位含对羟基苯并取代基的吡咯亚氨基海洋生物碱维乌他明。这一方法对于合成一些6-取代的吡咯亚氨基醌海洋生物碱类似物是有用的，这对于研究这类潜在的抗肿瘤化合物的构效关系是必不可少的(Tetrahedron Letters，1999，40,1713)。

Pyrroloiminoquinone marine alkaloids have received considerable attention due to their potential antitumor activity. In this reserch project we have developed new and efficient methods for both construction and functionalization of pyrroloiminoquinone nucleus based mainly upon directed lithiation strategy.Thus, 1-triisopropylsily-6-methoxygramine was chlorinated at 4-position of the indole ring via directed lithiation followed by a reaction with hexachloroethane. The chlorinated gramine was converted to 1-protected-6-methoxytryptamine derivatives by conventional procedure. The tryptamines were cyclized to the key tricyclic 7-methoxy- 1, 3, 4, 5 -tetrahydropyrrolo[4, 3, 2- de] quinolincs by aryne-mediated cyclization. The Fremy's salt or salcomine-catalyzed oxidation of the tricyclic compounds produced the 7-methoxy-pyrroloiminoquinones, which were converted to the pyrroloiminoquinone marine alkaloids makaluvamines A, D, 1, and K by the reactions with ammmonium chloride or tyramine hydrochloride (Tetrahedron, 1998, 54, 8999).Next, the 6-selective functionalization of 1, 3, 4, 5-tetrahydropyrrolo[4, 3, 2-de] quinoline nucleus has been developed via N-Boc-directed lithiation. By using this method, the first total synthesis of veiutamine, a new type of pyrroloiminoquinone marine alkaloid bearing a p-hydroxybenzyl substituent at C-6 position has been achieved. This procedure is useful for the synthesis of a number of 6-substituted pyrroloiminoquinone marine alkaloid analogues, which are essential for structure-activity relationshiip studies of this type of potential antitumor compounds (Tetrahedron Letters, 1999, 40, 1713).