A new total synthesis of the neuronal cell-protecting carbazole alkaloid carbazomadurin A is described. The key step was an allene-mediatedelectrocyclicreaction involving an indole [b]-bond for the construction of a highly substituted carbazole ring. The E-alkenyl side chain at the C1 position of carbazole was introduced between O-triflate and alkenyl pinacol borate using the Suzuki–Miyaura reaction
描述了神经细胞保护咔唑生物碱咔唑马杜林A的新的全合成。关键步骤是用于构建高度取代的咔唑环的涉及吲哚[ b ]键的异戊二烯介导的电环反应。使用Suzuki–Miyaura反应,将咔唑C1位置的E-烯基侧链引入O-三氟甲磺酸盐和烯基频哪醇硼酸酯之间。用TBAF裂解SEM组,并还原甲酰基以提供carbazomadurin A.
Stereo- and Regiocontrolled Methylboration of Terminal Alkynes
作者:Oleksandr Zhurakovskyi、Rafael M. P. Dias、Adam Noble、Varinder K. Aggarwal
DOI:10.1021/acs.orglett.8b01252
日期:2018.5.18
A scalable and operationally simplesynthesis of trisubstituted alkenyl boronic esters has been achieved using a Zr-catalyzed carboalumination of terminal alkynes followed by in situ transmetalation with i-PrOBpin. The products are formed in good yields and with excellent regioselectivity and perfect stereoselectivity. The new procedure provides a significant improvement over the previously reported
The totalsyntheses of the neuronal cell-protecting carbazole alkaloids carbazomadurin A and (S)-(+)-carbazomadurin B were achieved. The key step of the synthesis of the polysubstituted carbazole rings included an allene-mediatedelectrocyclicreaction of the 6π-electron system that involved the indole 2,3-bond. The cleavage of the alkoxy groups of the resulting 3-ethoxy-8-isopropoxycarbazole successfully