Zask Arie, Ellestad George
Department of Biological Sciences, Columbia University, New York, New York.
Department of Chemistry, Columbia University, New York, New York.
Chirality. 2018 Feb;30(2):157-164. doi: 10.1002/chir.22786. Epub 2017 Nov 15.
Racemic natural products are rarely produced in plants and microorganisms and are thought to be the result of nonenzymatic, spontaneous reactions. These compounds are often highly complex with multiple contiguous chiral centers that present a challenge to organic synthesis. Formation of these racemates often occurs by cyclization reactions that can generate multiple stereocenters from achiral precursors. Biomimetic synthesis of these racemic natural products provides support for their proposed nonenzymatic spontaneous biosynthesis. These elegant syntheses also provide scalable and efficient routes to these complex natural products. Although the number of reported racemic natural products is relatively low, an isolated natural product that has a very small optical rotation has been shown to be a true racemate. Thus, the occurrence of racemic natural products could be more common than thought.
外消旋天然产物在植物和微生物中很少产生，被认为是非酶促自发反应的结果。这些化合物通常高度复杂，具有多个相邻的手性中心，这对有机合成构成了挑战。这些外消旋体的形成通常通过环化反应发生，环化反应可以从非手性前体产生多个立体中心。这些外消旋天然产物的仿生合成支持了它们非酶促自发生物合成的假说。这些精妙的合成方法还为合成这些复杂天然产物提供了可扩展且高效的途径。尽管已报道的外消旋天然产物数量相对较少，但一种旋光度非常小的分离天然产物已被证明是真正的外消旋体。因此，外消旋天然产物的存在可能比想象的更为普遍。
