Abstract
Three title compounds, namely, 2-(4-chloro-benz-yl)-5-[(1H-indol-3-yl)meth-yl]-6-phenyl-imidazo[2,1-b][1,3,4]thia-diazole, C26H19ClN4S, (I), 2-(4-chloro-benz-yl)-6-(4-fluoro-phen-yl)-5-[(1H-indol-3-yl)meth-yl]imidazo[2,1-b][1,3,4]thia-diazole, C26H18ClFN4S, (II), and 6-(4-bromo-phen-yl)-2-(4-chloro-benz-yl)-5-[(1H-indol-3-yl)meth-yl]imidazo[2,1-b][1,3,4]thia-diazole, C26H18BrClN4S, (III), have been prepared using a reductive condensation of indole with the corresponding 6-aryl-2-(4-chloro-benz-yl)imidazo[2,1-b][1,3,4]thia-diazole-5-carbaldehydes (aryl = phenyl, 4-fluoro-phenyl or 4-bromo-phen-yl), and their crystal structures have been determined. The asymmetric unit of compound (I) consists of two independent mol-ecules and one of the mol-ecules exhibits disorder of the 4-chloro-benzyl substituent with occupancies 0.6289 (17) and 0.3711 (17). Each type of mol-ecule forms a C(8) chain motif built from N-H⋯N hydrogen bonds, which for the fully ordered mol-ecule is reinforced by C-H⋯π inter-actions. In compound (II), the chloro-benzyl unit is again disordered, with occupancies 0.822 (6) and 0.178 (6), and the mol-ecules form C(8) chains similar to those in (I), reinforced by C-H⋯π inter-actions involving only the major disorder component. The chloro-benzyl unit in compound (III) is also disordered with occupancies of 0.839 (5) and 0.161 (5). The mol-ecules are linked by a combination of one N-H⋯N hydrogen bond and four C-H⋯π inter-actions, forming a three-dimensional framework.
Highlights
Imidazo[2,1-b][1,3,4]thiadiazole is a versatile nucleus for the elaboration of novel heterocyclic compounds as it can readily be substituted at any position of 2, 5 or 6 (Khazi et al, 2011)
The recently reported indolinone derivative, 6-(4-bromophenyl)-2-(4-chlorobenzyl)-5-[(1H-indolin-2-one-3-yl)methylidene]imidazo[2,1-b][1,3,4]thiadiazole, has been shown to act as a powerful inhibitor of the anti-apoptotic protein BCL2, and to cause significant tumour regression without any significant side effects (Iyer et al, 2016; Vartak et al, 2016). With these observations in mind, we have synthesized analogues of disarib, replacing the indolinone substituent with an indolylmethyl unit, while at the same time varying the substituent in the 6-aryl ring, and here we report
The centrosymmetric space group for the compounds (I) and (II) show that these have crystallized as conformational racemates
Summary
Imidazo[2,1-b][1,3,4]thiadiazole is a versatile nucleus for the elaboration of novel heterocyclic compounds as it can readily be substituted at any position of 2, 5 or 6 (Khazi et al, 2011). The recently reported indolinone derivative, 6-(4-bromophenyl)-2-(4-chlorobenzyl)-5-[(1H-indolin-2-one-3-yl)methylidene]imidazo[2,1-b][1,3,4]thiadiazole (disarib), has been shown to act as a powerful inhibitor of the anti-apoptotic protein BCL2, and to cause significant tumour regression without any significant side effects (Iyer et al, 2016; Vartak et al, 2016). With these observations in mind, we have synthesized analogues of disarib, replacing the indolinone substituent with an indolylmethyl unit, while at the same time varying the substituent in the 6-aryl ring, and here we report.
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