Synthesis of new 6-(arene)chromium tricarbonyl complexes with 1,3-benzodioxole and 1,4-benzodioxane ligands

Particular interest in studying the structure and features of chemical behavior of heterocyclic compounds containing two oxygen atoms in their composition is associated with their wide distribution in nature, as well as with their high biological activity. For the first time, we present data on the possibility of obtaining and studying a number of physicochemical properties and spectral characteristics of some η6-(arene)chromium tricarbonyl complexes of pyrocatechol cyclic esters. At the first stage of our investigation the interaction of pyrocatechol (1) with dichloromethane, 1,2-dichloroethane and benzaldehyde has been used to synthesize the corresponding cyclic esters, such as 1,3-benzodioxole (2), 1,4-benzodioxane (3) and 2-phenyl-1,3-benzodioxole (4). Then the π-complexes have been obtained by two independent methods: the reaction of compounds (2), (3), and (4) with chromium hexacarbonyl (method A) and triamminechromium tricarbonyl (method B). Method A synthesis has been carried out by reacting the abovementioned compounds 2-4 with chromium hexacarbonyl in refluxing dibutyl ether or in a mixture of diglyme/octane (1:1). The reactions probably proceed with partial decomposition of the resulting π-complexes. Higher yields are observed when reactions are carried out by method B, which uses chromium hexacarbonyl derivatives, namely triamminechromium tricarbonyl, in a dioxane solution. It has been shown that the latter method not only gives higher yields, but also makes it possible to synthesize a wider range of heterocyclic chromium π-complexes. The composition and structure of the obtained compounds have been determined using various physico-chemical analysis methods, such as HPLC, UV, IR, 1H NMR spectrometry, and mass spectrometry.