Crystal structure of 2-acetyl-5-(3,4-di­meth­oxy­phen­yl)-6-eth­oxy­carbonyl-3,7-dimethyl-5H-thia­zolo[3,2-a]pyrimidin-8-ium chloride

The title mol-ecular salt, C21H25N2O5S(+)·Cl(-), crystallizes with two ion pairs in the asymmetric unit. The cations have similar conformations (r.m.s. overlay fit = 0.40 Å), with one of them showing disorder of the terminal methyl group of the ester in a 0.72 (2):0.28 (2) ratio. In the first cation, the 3,4-dimeth-oxy-substituted phenyl ring subtends a dihedral angle of 88.38 (7)° with the pyrimidine ring and 6.79 (8)° with the thia-zole ring. The equivalent data for the second cation are 89.97 (3) and 6.42 (7)°, respectively. The pyrimidine ring adopts a sofa conformation in each cation. In the crystal, the components are linked by N-H⋯Cl hydrogen bonds, generating isolated ion pairs. The ion pairs are are linked by C-H⋯O inter-actions, generating a three-dimensional network. In addition, a weak C-H⋯π inter-action is observed.