The depsidones divaronic acid (24) (8-hydroxy-3-methoxy-1,6-dipropyl-11- oxo -11H- dibenzo [ b,e ][1,4]dioxepin-7-carboxylic acid) and stenosporonic acid (25) (8-hydroxy-3-methoxy-6-pentyl-l-propyl-ll-oxo-l1H-dibenzo[ b,e ][1,4]dioxepin-7-carboxylic acid) have been prepared by unambiguous synthesis, and have been shown to cooccur with colensoic acid, atranorin and chloroatranorin in the lichen Paraparmelia mongaensis. The syntheses employed a novel biomimetic-type approach which involved a Smiles rearrangement of a precursor meta-depside in the key step. This rearrangement has important biosynthetic implications and may account for the natural occurrence of isostructural depside-depsidone pairs.
去苷酮体 divaronic acid (24) (8-羟基-3-甲氧基-1,6-二丙基-11-氧代-11H-二苯并[b,e][1,4]二氧杂卓-7-羧酸)和 stenosporonic acid (25) (8-羟基-3-甲氧基-6-戊基-l-丙基-ll-氧代-l1H-二苯并[b、e][1,4]二氧杂环庚烷-7-羧酸),并证明它们在地衣 Paraparmelia mongaensis 中与可乐宁酸、阿特拉诺林和氯阿特拉诺林共存。这些合成采用了一种新颖的生物模拟方法,在关键步骤中对前体元苷进行斯迈尔斯重排。这种重排具有重要的生物合成意义,可能是天然存在等结构苷元对的原因。