A Biosynthetically-Inspired Chemical Synthesis of Naturally Occurring Halogenated Medium Ring Ethers from Laurencia

海藻和海藻含有丰富的天然溴和氯(卤化)天然产物。特别是，劳伦西亚物种提供了中环醚(由7，8或9个原子组成的环，由一个氧组成，其余为碳)等卤化化合物，这些化合物传统上被认为很难在实验室中合成。以前，这些化合物的生物发生被认为涉及酒精在活性溴离子上的循环，以产生中间环。然而，目前提出的生物发生学存在一些无法解释的困难。我们现在提出，酒精不是真正的生物发生前体。考虑到来自Laurencia物种的代谢物的各种构型，可以从替代的公共前体提出统一的生物合成方案，这些前体是弹簧加载的，以克服与制造中等尺寸环相关的传统困难。

Seaweeds and alga provide a rich source of naturally occurring bromine and chlorine (halogenated) containing natural products. In particular, Laurencia species provide such halogenated compounds as medium ring ethers (rings of 7,8 or 9-atoms consisting of one oxygen and the rest as carbon) that have traditionally been viewed as difficult to synthesize in a laboratory. Previously, the biogenesis of these compounds has been assumed to involve the cyclisation of an alcohol onto a reactive bromonium ion to create the medium ring. However, there are some unexplained difficulties with the currently proposed biogenesis. We now propose that alcohols are not the true biogenetic precursors. Consideration of the various configurations of the metabolites from Laurencia species allows a unifying biosynthetic scheme to be proposed from an alternative common precursor, which are spring-loaded to overcome the traditional difficulties associated with making medium-sized rings.