A concise synthesis of spirotryprostatin A.

The preparation of two new synthons, 2,5- and 2,6-dibromotryptophan esters, and their use in diastereoselective intramolecular N-acyliminium ion spirocyclization methodology for the rapid construction of spirotryprostatin A and analogues are described.

Preparation and synthetic applications of 2-halotryptamines: synthesis of elacomine and isoelacomine.

The preparation of 2-halotryptamines from tryptamine is described. New stereoselective intramolecular iminium ion spirocyclization methodology for the construction of spiro[pyrrolidine-3,3'-oxindoles] is outlined in synthetic studies of elacomine (1) and isoelacomine (2). [reaction: see text]

Synthesis of marine sponge bisindole alkaloids dihydrohamacanthins.

[structure: see text] A convergent synthesis of the marine sponge bisindole alkaloids dihydrohamacanthins is described. The synthesis centers on the construction of 3,5- and 3,6-linked pyrazinones and their reduction to the requisite piperazinones with sodium cyanoborohydride.