First Total Synthesis of (±)-Flustraminol B

A first route for the synthesis of a 6-brominated marine alkaloid, flustraminol B (1), is reported using 2,6-dibromoindole (3b) as a key starting material. Bromine atoms were introduced regioselectively to 2b using NBS. The crucial selective reductive cyclization of the corresponding 6-brominated-2,3-dioxindole (7b) was successfully controlled using Red-Al® in toluene, leading to 6-brominated pyrroloindole (8), which by selective N-methylation gave flustraminol B (1).