Ethylenediamine → Carbazole

Participants

Reaction Conditions

Reaction Steps

3,6-Bis-(5-indolyl)carbazole-2′,2′-dicarboxylic acid diethyl ester (0.7 mmol) was dissolved in 3.5 mL ethylenediamine in an amber glass vial with a Teflon screw-cap and heated at 55° C. in a sand-bath overnight. The excess amine was removed under vacuum and the residue was dissolved in 7 mL DMSO, 0.7 mL TFA was added and the solution was added up to 35 mL by H2O. The solution was purified by preparative HPLC in 7 injections. Fractions containing 3,6-Bis-(5-indolyl)carbazole-2′,2′-bis(2-aminoethyl)carboxamide were pooled and evaporated. The residues were combined and used in the next step as such. Step 5: 3,6-Bis-(5-indolyl)carbazole-2′,2′-bis(2-aminoeth-1-yl)carboxamide bistrifluoroacetate (0.5 mmol) was mixed with 2.5 mL DMF, 10 mmol diisopropylethyamine and 5 mmol pyrazole-1-carboxamidine hydrochloride were added and the resulting solution was heated at 55° C. for 24 hr. The solvent was removed under vacuum and the residue was dissolved in 5 mL DMSO, 0.5 mL TFA was added and the solution was added up to 25 mL by H2O. The solution was purified by preparative HPLC in 5 injections. Appropriate fractions were pooled and evaporated. The residue was dissolved in 5 mL MeOH, divided into 5 centrifuge tubes and cooled in dry ice for 5 min. One mL of 2 N HCl solution in dioxane was added to each tube and the solutions were immediately diluted to 40 mL each by cold Et2O. The suspensions were centrifuged and the supernatant liquids were decanted. The cakes were dissolved in 1 mL MeOH each and precipitated with cold Et2O. The suspensions were centrifuged and the supernatant liquids were decanted. The residues were dissolved in water and lyophilized to yield 3,6-bis{2-[N-2-guanidinoeth-1-yl)amido]-1H-indol-5-yl}-9H-carbazole.

Provenance & Evidence