Regiospecific synthesis of mono-N-substituted indolopyrrolocarbazoles.
[reactions: see text] Two complementary and efficient strategies have been developed for the regiospecific synthesis of unsymmetrical indolopyrrolocarbazoles (IPCs) mono-N-substituted with a pentacycle. A halogen in position 2 of the intermediate bisindolylmaleimides 3a-e allows a selective Mitsunobu coupling by exploiting the increased acidity of the 2-chloro-substituted indole nitrogen. It also promotes an easier cyclization of bisindolylmaleimides 4a-e and 7b-e to IPCs. Alkylation of the 2-unsubstituted indole-3-carboxamides 2a,b and further processing to the corresponding IPCs gives access to the opposite regioisomers.
Fröhner
Wolfgang
W
Chemistry Department, Sirenade Pharmaceuticals AG, Am Klopferspitz 19a, D-82152 Martinsried, Germany.
Monse
Barbara
B
Braxmeier
Tobias M
TM
Casiraghi
Laura
L
Sahagún
Heidi
H
Seneci
Pierfausto
P
D000478:Alkylation; D002227:Carbazoles / Q000138:chemical synthesis* / Q000737:chemistry; D003500:Cyclization; D006027:Glycosides / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D013237:Stereoisomerism
D002227:Carbazoles; D006027:Glycosides