A Concise Synthesis of Topsentin A and Nortopsentins B and D

[reaction: see text] A concise synthesis of topsentin A (R(1) = R(2) = H) and nortopsentins B (R(1) = Br, R(2) = H) and D (R(1) = R(2) = H) is described from oxotryptamine 5 via reduction of acyl cyanide 4. Regiospecific bromination of 3-cyanoindole afforded 6-bromo-3-cyanoindole (10) as the major product.