Department of Chemistry, Temple University, Philadelphia, PA, USA.
Methods Mol Biol. 2022;2505:101-112. doi: 10.1007/978-1-0716-2349-7_8.
Enzymatic biotransformation has become a widely used technique in synthetic chemistry to achieve difficult chemical transformations. Cytochrome P450 monooxygenase enzymes found in nature carry out a wide range of difficult chemical reactions, such as the oxidation of the monoterpene indole alkaloid (-)-tabersonine at the unreactive 16th position on the indoline benzene ring in the biosynthesis of biologically active natural products such as the bis-indole alkaloid (-)-melodinine K. Herein, we describe the first semisynthesis of (-)-melodinine K enabled by a biological gram scale route to the northern fragment, (-)-16-hydroxytabersonine, as well as a chemical route to the southern fragment, (-)-pachysiphine, both derived from (-)-tabersonine and subsequently coupled in only eight linear steps. (-)-16-Hydroxytabersonine is produced through an enzymatic biotransformation with a genetically modified Saccharomyces cerevisiae yeast strain expressing a tabersonine 16-hydroxylase enzyme to enable regioselective oxidation on multigram scale, and (-)-pachysiphine is produced through stereoselective and regioselective epoxidation of the disubstituted alkene.
酶促生物转化已成为合成化学中广泛使用的技术，可实现困难的化学转化。自然界中发现的细胞色素 P450 单加氧酶可进行广泛的困难化学反应，例如在生物活性天然产物如双吲哚生物碱（-）-melodinine K 的生物合成中，对吲哚苯并环上的 16 位（-）-tabersonine 进行氧化。在此，我们描述了通过生物克规模途径到北方片段（-）-16-羟基-tabersonine 的半合成首次实现了（-）-melodinine K，以及化学途径到南方片段（-）-pachysiphine，两者均来自（-）-tabersonine，随后仅通过八个线性步骤偶联。（-）-16-羟基-tabersonine 通过具有表达 tabersonine 16-羟化酶的基因修饰酿酒酵母酵母菌株的酶促生物转化产生，以实现克级规模的区域选择性氧化，（-）-pachysiphine 通过取代烯烃的立体选择性和区域选择性环氧化产生。
