General syntheses of 1-alkyltoxoflavin and 8-alkylfervenulin derivatives of biological significance by the regioselective alkylation of reumycin derivatives and the rates of transalkylation from 1-alkyltoxoflavins into nucleophiles
作者:Tomohisa Nagamatsu、Hirofumi Yamasaki
DOI:10.1039/b007302o
日期:——
Regioselective alkylations of reumycin derivatives under alkaline conditions with a dialkyl sulfate or alkyl halide in 1,4-dioxane or DMF to provide 1-alkyltoxoflavin or 8-alkylfervenulin derivatives of biological significance, are described. Namely, the primary and secondary alkylations of reumycin derivatives with appropriate dialkyl sulfates or alkyl bromides under alkaline conditions in 1,4-dioxane gave predominantly 1-alkyltoxoflavin derivatives, while the same alkylations in DMF instead of 1,4-dioxane gave predominantly 8-alkylfervenulin derivatives. In the case of tertiary alkylation, the reumycin derivative with 2-bromo-2-methylpropane in both solvents under the same conditions yielded only the 1-alkyltoxoflavin derivative. Moreover, the rates of transalkylation from 1-alkyltoxoflavin derivatives into nucleophiles, e.g. DMF and n-butylamine, are also described. That is, the toxoflavin derivatives possessing a primary alkyl group at the 1-position were easily dealkylated from the 1-position by heating with DMF, whereupon reumycin (i.e., 1-dealkyltoxoflavin, 8-dealkylfervenulin) derivatives were formed. In other words, transalkylation from the toxoflavin derivatives into DMF took place. However, the transalkylation of 1-alkyltoxoflavin derivatives possessing a secondary or tertiary alkyl group at the 1-position was not observed under such conditions. On the other hand, when heating 1-alkyltoxoflavin derivatives with n-butylamine in 1,4-dioxane, the transalkylations were more easily observed even in the case of 1-alkyltoxoflavin derivatives substituted by a tertiary alkyl group.
在碱性条件下,使用二烷基硫酸酯或烷基卤化物在1,4-二恶烷或DMF中对reumycin衍生物进行区域选择性烷基化,生成具有生物学意义的1-烷基toxoflavin或8-烷基fervenulin衍生物,本文对此进行了描述。即,在碱性条件下,使用适当的二烷基硫酸酯或烷基溴化物在1,4-二恶烷中对reumycin衍生物进行伯和仲烷基化,主要生成1-烷基toxoflavin衍生物,而在DMF中替代1,4-二恶烷进行同样的烷基化,则主要生成8-烷基fervenulin衍生物。在叔烷基化的情况下,在相同条件下,使用2-溴-2-甲基丙烷在两种溶剂中的reumycin衍生物仅生成1-烷基toxoflavin衍生物。此外,还描述了从1-烷基toxoflavin衍生物向亲核试剂(例如DMF和正丁胺)的转移烷基化速率。也就是说,在1-位具有伯烷基的toxoflavin衍生物通过与DMF加热容易从1-位去烷基化,随后形成reumycin(即1-去烷基toxoflavin,8-去烷基fervenulin)衍生物。换言之,从toxoflavin衍生物向DMF发生了转移烷基化。然而,在1-位具有仲或叔烷基的1-烷基toxoflavin衍生物的转移烷基化在这些条件下未被观察到。另一方面,当在1,4-二恶烷中加热1-烷基toxoflavin衍生物与正丁胺时,即使在1-位上被叔烷基取代的1-烷基toxoflavin衍生物的情况下,转移烷基化也更容易被观察到。