Verrucine F, a Quinazoline from Penicillium verrucosum
摘要:
Verrucine F (3), a quinazoline similar to verrucines A (1) and B (2), contains one anthranilic acid residue, one L-glutamine residue, and one alpha,beta-unsaturated phenylalanine residue, as determined by NMR, MS, and chemical methods. Compounds I and 3, but not 2, were produced by Penicillium verrucosum J255 and eight additional P. verrucosum strains. Verrucines were typically more concentrated in the inner (older) parts of the colony, and 3 peaked 4-8 days after 1, but at 10-fold lower concentrations (similar to 200 mu g/g). Verrucine F (3) formed spontaneously from 1 in buffered water solutions. probably by oxidation at C-1 followed by water elimination.
The total synthesis of cyclotripeptidic natural products possessing a central piperazino[2,1-b]quinazolin-3,6-dione core is described through an original strategy involving the pivotal cyclocondensation of an electrophilic homoserine lactone intermediate. The alkylidene group was spontaneously installed by autoxidation during the cyclocondensation process, while the propionamide side chain was introduced
通过涉及亲电子高丝氨酸内酯中间体的关键环缩合的原始策略描述了具有中心哌嗪[2,1- b ]喹唑啉-3,6-二酮核心的环三肽天然产物的全合成。亚烷基是在环缩合过程中通过自氧化自发安装的,而丙酰胺侧链是通过溴乙基中间体的镍催化氨基羰基化引入的。对于这种高度功能化的中间体来说,最后的反应是前所未有的。最后,我们探索了天然产物的结构修饰和相互转化。总体而言,这项工作产生了 anacine、aurantiomide C、polonimides A 和 C 以及 verrucine F。