Crystal structures of four indole derivatives as possible cannabinoid allosteric antagonists

Abstract

The crystal structures of four indole derivatives with various substituents at the 2-, 3- and 5-positions of the ring system are described, namely, ethyl 3-(5-chloro-2-phenyl-1H-indol-3-yl)-3-phenylpropanoate, C25H22ClNO2, (I), 2-bromo-3-(2-nitro-1-phenylethyl)-1H-indole, C16H13BrN2O2, (II), 5-methoxy-3-(2-nitro-1-phenylethyl)-2-phenyl-1H-indole, C23H20N2O3, (III), and 5-chloro-3-(2-nitro-1-phenylethyl)-2-phenyl-1H-indole, C22H17ClN2O2, (IV). The dominant intermolecular interaction in each case is an N—H...O hydrogen bond, which generates either chains or inversion dimers. Weak C—H...O, C—H...π and π–π interactions occur in these structures but there is no consistent pattern amongst them. Two of these compounds act as modest enhancers of CB1 cannabanoid signalling and two are inactive.