Bio‐Inspired Dimerization Reaction of Tryptophan Derivatives in Aqueous Acidic Media: Three‐Step Syntheses of (+)‐WIN 64821, (−)‐Ditryptophenaline, and (+)‐Naseseazine B

Doubling up: The direct bio-inspired dimerization of commercially available amine-free tryptophan derivatives in aqueous acidic media provides C2-symmetrical and nonsymmetrical dimeric compounds. Further processing completes the concise syntheses of naturally occurring dimeric diketopiperazine alkaloids such as (+)-WIN 64821 (see picture) in overall yields of up to 20 %.