Decarboxylative Halogenation of Indolecarboxylic Acids Using Hypervalent Iodine(III) Reagent and Its Application to the Synthesis of Polybromoindoles
摘要:
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
摘要:
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.