Department of Chemistry, Villanova University, Villanova, Pennsylvania 19085, United States.
Natural Products Utilization Research Unit, Agricultural Research Service, United States Department of Agriculture, P. O. Box 1848, University, Mississippi 38677, United States.
J Agric Food Chem. 2020 Sep 16;68(37):9906-9916. doi: 10.1021/acs.jafc.0c02564. Epub 2020 Sep 2.
Stereoselective syntheses of new pyranopyrans that are related to the natural product diplopyrone, which is a phytotoxin implicated in cork oak decline, have been achieved from carbohydrate starting materials in two approaches that are based on -glycosides as key intermediates. A -alkynyl glycoside prepared by Ferrier rearrangement was used as the precursor to a new pyranopyran alkyne that showed potent antibacterial activity against the common bacterial pathogen that causes enteric septicemia in catfish. The -alkynyl glycoside also showed herbicidal activity. New bioassay data for the pyranopyran nitrile (4a,6,8a)-6-cyano-6,8a-dihydropyrano-[3,2-]pyran-2(4a)-one, the most potent of the pyranopyrans synthesized to date, were obtained in greenhouse studies that revealed additional herbicidal activity. Other new analogues that were synthesized included desmethylpyranopyrans that were prepared by Isobe -alkynylation-rearrangement/reduction and RCM-based pyranopyran construction. The antibiotic and phytotoxic activities of the new pyranopyrans synthesized in this study highlight the importance of substituents on the nonlactone ring and demonstrate the potential of such compounds as antibiotics and herbicides.
已从碳水化合物起始原料通过两种方法实现了与天然产物二吡喃酮（一种与栓皮栎衰退有关的植物毒素，被认为是引起鲶鱼肠败血症的常见细菌病原体）相关的新型吡喃并吡喃的立体选择性合成，这两种方法均基于 -糖苷作为关键中间体。通过 Ferrier 重排制备的 -炔基糖苷被用作新的吡喃并吡喃炔的前体，该炔显示出对常见细菌病原体的强大抗菌活性，该病原体导致鲶鱼肠败血症。-炔基糖苷还显示出除草活性。在温室研究中获得了用于吡喃并吡喃腈（4a，6，8a）-6-氰基-6，8a-二氢吡喃-[3，2-]吡喃-2（4a）-酮的新生物测定数据，这是迄今为止合成的最有效的吡喃并吡喃，该酮在温室研究中揭示了额外的除草活性。还合成了其他新的类似物，包括通过 Isobe-炔基化-重排/还原和基于 RCM 的吡喃并吡喃构建制备的去甲吡喃并吡喃。本研究中合成的新型吡喃并吡喃的抗生素和植物毒性活性强调了非内酯环上取代基的重要性，并证明了此类化合物作为抗生素和除草剂的潜力。
