Total Synthesis of Natural and Unnatural Lamellarins with Saturated and Unsaturated D-Rings
摘要:
Twenty-eight natural and unnatural lamellarins with either a saturated or an unsaturated D-ring were synthesized according to our developed synthetic route. The key step involved the Michael addition/ring closure (Mi-RC) of the benzyldihydroisoquinoline and alpha-nitrocinnamate derivatives, which provided the 2-carboethoxypyrrole intermediates in moderate to good yields (up to 78% yield). Subsequent hydrogenolysis/lactonization furnished lamellarins with a saturated D-ring in excellent yields (up to 93% yield). DDQ oxidation of the saturated lamellarin acetates led directly to the corresponding unsaturated analogues in 54-95% yield. In addition, only two steps in our developed strategy require column chromatography.
Total Synthesis of Natural and Unnatural Lamellarins with Saturated and Unsaturated D-Rings
摘要:
Twenty-eight natural and unnatural lamellarins with either a saturated or an unsaturated D-ring were synthesized according to our developed synthetic route. The key step involved the Michael addition/ring closure (Mi-RC) of the benzyldihydroisoquinoline and alpha-nitrocinnamate derivatives, which provided the 2-carboethoxypyrrole intermediates in moderate to good yields (up to 78% yield). Subsequent hydrogenolysis/lactonization furnished lamellarins with a saturated D-ring in excellent yields (up to 93% yield). DDQ oxidation of the saturated lamellarin acetates led directly to the corresponding unsaturated analogues in 54-95% yield. In addition, only two steps in our developed strategy require column chromatography.
A bottom-up synthesis of lamellarinsG, J, L, and Z was achieved via one-pot halogen dance/Negishi coupling of a lithiated dibromopyrrole derivative. The easily accessible dibromopyrrole bearing an ester moiety underwent halogen dance smoothly at −78 °C within 10 min. The resultant α-pyrrolyllithium was transmetalated to the corresponding organozinc species, which was then coupled with an aryl iodide
层状蛋白 G、J、L 和 Z 的自下而上合成是通过锂化二溴吡咯衍生物的一锅卤素舞蹈/Negishi 偶联实现的。易于获得的带有酯部分的二溴吡咯在-78°C 下10 分钟内顺利进行了卤素舞蹈。得到的 α-吡咯锂被金属转移到相应的有机锌物质上,然后在催化钯的存在下与芳基碘化物偶联以提供完全取代的吡咯。随后进行卤素 - 锂交换以仅在靠近酯部分的 β 位置掺入硼酸酯基团。这种合成中间体允许逐步二芳基化,用于层状蛋白 G、J、L 和 Z 的全合成。
Total Synthesis of Natural and Unnatural Lamellarins with Saturated and Unsaturated D-Rings
作者:Poonsakdi Ploypradith、Thaninee Petchmanee、Poolsak Sahakitpichan、Nichole D. Litvinas、Somsak Ruchirawat
DOI:10.1021/jo061810h
日期:2006.12.1
Twenty-eight natural and unnatural lamellarins with either a saturated or an unsaturated D-ring were synthesized according to our developed synthetic route. The key step involved the Michael addition/ring closure (Mi-RC) of the benzyldihydroisoquinoline and alpha-nitrocinnamate derivatives, which provided the 2-carboethoxypyrrole intermediates in moderate to good yields (up to 78% yield). Subsequent hydrogenolysis/lactonization furnished lamellarins with a saturated D-ring in excellent yields (up to 93% yield). DDQ oxidation of the saturated lamellarin acetates led directly to the corresponding unsaturated analogues in 54-95% yield. In addition, only two steps in our developed strategy require column chromatography.