Synthesis of arcyriarubine regioisomers by Pd(0)-catalysis or via lithiated indole derivatives - conformational analysis by semiempirical and X-ray methods

Abstract

Regioisomers of arcyriarubines were synthesized by the reaction of N-protected indoles with dibromomaleimide either in the presence of a Pd(0)-catalyst or n-BuLi. Methods for N-alkylation of these bisindolylmaleimides and deprotection of the indole-N are described. The structure of the bisindolylmaleimide I (R = R1 = R2 = H) was studied by semiempiric quantum-chem. calcns., the structure of its deriv. I (R = CH2CH2Br, R1 = SO2Ph, R2 = H) was ascertained by X-ray anal.