Syntheses and Crystal Structures of 2-Chloromethyl-3,5-dimethyl-4-methoxy/ethoxy-pyridines and Their Methylsulphinyl Derivatives

Abstract

Treatment of 2-(chloromethyl)-pyridine derivatives 3,5-dimethyl-4-(alkoxy)-2-(chloromethyl)-pyridine hydrochloride (alkoxy = methoxy, 1; ethoxy, 2) with 1-(4-chloro-phenyl)imidazole-2-thione in the presence of sodium methoxide afforded the corresponding methylsulphinyl derivatives 3,5-dimethyl-[4-(alkoxy)-2-pyridinyl]-methylthio-1-(4-chloro-phenyl)-imidazole (alkoxy = methoxy, 3; ethoxy, 4). Similarly, reaction of 1 or 2 with 4,6-dimethyl-pyrimidine-2-thiol gave the methylsulphinyl derivatives 3,5-dimethyl-[4-(alkoxy)-2-pyridinyl]-methylthio-4,6-dimethyl-pyrimidine (alkoxy = methoxy, 5; ethoxy, 6). While reaction of 5 with CuCl₂·2H₂O in methanol produced a square-planar copper(II) complex, trans-bis{3,5-dimethyl-[4-(methoxy)-2-pyridinyl]-methylthio-4,6-dimethyl-pyrimidine}-dichloro-copper(II) (7). The crystal structures of 1, 2, 4⋅HCl⋅2H₂O, and 7, along with their spectroscopic properties are reported. The weak hydrogen-bonding interactions exist in compounds 1, 2, and 4⋅HCl⋅2H₂O. Compound 1 crystallizes in the monoclinic space group P2₁/c with a = 6.074(11), b = 19.88(4), c = 9.230(16) Å, β = 99.67(4)°, and Z = 4. Compound 2 crystallizes in the monoclinic space group P2₁/n with a = 10.0103(15), b = 7.9905(12), c = 15.120(2) Å, β = 93.924(2), and Z = 4. The unit cells of both 4⋅HCl⋅2H₂O and 7 have triclinic P-1 symmetry with the cell parameters a = 7.492(8), b = 10.170(12), c = 15.723(18) Å, α = 77.159(15)°, β = 91.113(13)°, γ = 81.194(16)°, and V = 1152(2) Å³ for 4⋅HCl⋅2H₂O and a = 10.526(2), b = 12.936(2), c = 14.455(3) Å, α = 107.929(2)°, β = 93.686(2)°, γ = 104.095(3)°, and V = 1734.3(6) ų for 7.

Graphical Abstract

Interaction of 3,5-dimethyl-[4-(methoxy)-2-pyridinyl]-methylthio-4,6-dimethyl-pyrimidine and CuCl₂·2H₂O in methanol resulted in the formation of a square-planar copper(II) complex, trans-bis{3,5-dimethyl-[4-(methoxy)-2-pyridinyl]-methylthio-4,6-dimethyl-pyrimidine}-dichloro-copper(II), which was structurally characterized.