A Novel Methodology for Preparing 5-Chloro- and 5-Bromotryptamines and Tryptophanes, and Its Application to the Synthesis of (±)-Bromochelonin B

Absnact -A novel methodology for introducing chlorine or bromine into the 5-position of tryptamines was found through 1-hydroxytryptamines.The chemistry was applied to the syntheses of (?)-5-chloro-, -5-bromotryptophan derivatives, and (2)-bromochelonin B.Many biologically active tryptamines are reported such as 5-bromotryptophan2 (I), bromochelonin B3 (2), alternatamide c4 (3), cyclocinamide A~ and so on, containing halogen at the 5-position of indole nucleus (Figure I ) .~ Their total syntheses would require suitably halogenated indolic building blocks.We have thusfar disclosed unprecedented acid promoted nucleophilic substitution reactions of 1-hydroxyindoles7 and succeeded in preparing 5-hydroxy-and 5-methoxytryptamines (I and n) as summarized in Table I .~ Now, we wish to describe that the reaction of 1-hydroxytryptamines with hydrogen halides is a suitable synthetic methodology for 5-chloro-and 5-bromotryptamines (43b and5a,b), and its applications to the syntheses of (?)-5-chloro-and 4-bromotryptophan derivatives (6qb and 7), and (?)-2.