3-Chloro-4-(5-methoxy-1H-indol-3-yl)cyclobut-3-ene-1,2-dione

The indole ring system is a prominent partial structure of several protein kinase inhibitor families. The title compound is the first example of a 5-substituted indolyl squaryl chloride with free indole nitrogen. It has been synthesized by reaction of 5-methoxyindole with squaric acid dichloride in diethyl ether and its IR, 1H-NMR, 13C-NMR, MS, UV and HPLC data are presented. This compound may prove to be a rather useful building block for the preparation of various derivatives for biological studies.