Synthesis of Bromoindole Alkaloids from <i>Laurencia </i><i>brongniartii</i>
作者:Oscar R. Suárez-Castillo、Lidia Beiza-Granados、Myriam Meléndez-Rodríguez、Alejandro Álvarez-Hernández、Martha S. Morales-Ríos、Pedro Joseph-Nathan
DOI:10.1021/np060406a
日期:2006.11.1
A regioselective synthesis of N-carbomethoxy-2,3,5-tribromoindole (6) via a sequential one-pot bromination-aromatization-bromination of N-carbomethoxyindoline (2) is described. The process for the transformation of 2 into 6 permitted the isolation of stable reaction intermediates N-carbomethoxy-5-bromoindoline (3), N-carbomethoxy-5-bromoindole (4), and N-carbomethoxy-3,5-dibromoindole (5). Compound
Hypervalent iodine mediated decarboxylative halogenation of indoledicarboxylic acid derivatives was studied. The treatment of 1-methylindole-2,3-dicarboxylic acid with phenyliodine diacetate (PIDA) in the presence of lithium bromide gave 1-methyl-3,3-bromooxindole. However, the reaction of 1-(phenylsulfonyl)indole-2,3-dicarboxylic acid with PIDA in the presence of lithium bromide afforded 2,3-dibromo-1-(phenylsulfonyl)indole. In a similar manner, the 2,3-dichloro- and 2,3-diiodoindole derivatives could be obtained by the reaction of the indole-2,3-dicarboxylic acids with PIDA in the presence of lithium chloride and iodide. This method was optimized to the synthesis of polybromoindole alkaloids.
Decarboxylative Bromination of Indole-2,3-dicarboxylic Acids Using Oxone® or CAN in the Presence of Lithium Bromide
The treatment of 1-methylindole-2,3-dicarboxylic acid with Oxone (R) and lithium bromide produced 3,3-dibromo-1-methyloxindole. However, the reaction of 1-benzenesulfonylindole-2,3-dicarboxylic acid with Oxone (R) and lithium bromide afforded 1-benzenesulfonyl-2,3-dibromoindole. In a similar manner, 2,3,5,6-tetrabromoindole was synthesized from 1-benzenesulfonyl-5,6-dibromoindole-2,3-dicarboxylic acid.
DA SETTIMO A.; SANTERINI V.; PRIMOFIORE G.; BIAGI G.; VENEZIANO C., GAZZ. CHIM. ITAL. <GCIT-A9>, 1977, 107, NO 7-8, 367-372