Iwamoto Osamu, Shinohara Ryoko, Nagasawa Kazuo
Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588, Japan.
Chem Asian J. 2009 Feb 2;4(2):277-85. doi: 10.1002/asia.200800382.
Playing the sax: The enantioselective total syntheses of (-)- and (+)-decarbamoyloxysaxitoxin (doSTX) and (+)-saxitoxin (STX) are reported. A new methodology was developed for the synthesis of STXs, featuring discriminative reduction of the nitro group and N-O bond in nitroisoxazolidine. Enantioselective total syntheses of (-)- and (+)-decarbamoyloxysaxitoxin (doSTX) and (+)-saxitoxin (STX) were achieved. The characteristic spiro-fused cyclic guanidine structure of STX was constructed by oxidation at the C4 position with IBX via an alpha-iminium carbonyl intermediate and acid-promoted cyclization of guanidine at the C5 position. A second-generation methodology was developed for the synthesis of STX, featuring discriminative reduction of the nitro group and N-O bond in nitroisoxazolidine. This approach provides efficient access to the key diamine intermediate for STXs.
报道了(-)-和(+)-脱氨甲酰氧基石房蛤毒素（doSTX）以及(+)-石房蛤毒素（STX）的对映选择性全合成。开发了一种用于合成石房蛤毒素的新方法，其特点是对硝基异恶唑烷中的硝基和N-O键进行选择性还原。实现了(-)-和(+)-脱氨甲酰氧基石房蛤毒素（doSTX）以及(+)-石房蛤毒素（STX）的对映选择性全合成。石房蛤毒素独特的螺环稠合环状胍结构是通过在C4位用IBX氧化，经由α-亚胺羰基中间体，以及在C5位用酸促进胍的环化反应构建而成。开发了第二代合成石房蛤毒素的方法，其特点是对硝基异恶唑烷中的硝基和N-O键进行选择性还原。该方法为石房蛤毒素的关键二胺中间体提供了有效合成途径。
