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Sulfimide and sulfoximide derivatives of benzo[b]thiophene

Sulfoximides (sulfoximines) are often described as “chemical chameleons” due to the variety of their reactions and especially to the potential of the sulfur atom as a stereogenic centre and the possibility for use in the asymmetric syntheses. Nevertheless, there are only few examples of vinyl sulfoximides in cycloaddition reactions [1]. Heterocyclic sulfoximide, 2, 3-dihydrobenzo[b]thiophene-1-imide 1-oxide, was synthesised early in 1965. by imination of 2, 3-dihydrobenzo[b]thiophene 1-oxide with hydrazoic acid. On the other side, heterocyclic sulfoximides where both carbons attached to sulfur are part of aromatic ring systems are more difficult to prepare and require different strategies [1]. Only recently, sulfimide (sulfilimine) and sulfoximide derivatives of monocyclic thiophene were prepared in the laboratory of Nakayama et al. [2]. Sulfoximide analogues of benzo[b]thiophene have not been reported yet, to the best of our knowledge. Our previous research includes 1, 3-dipolar cycloaddition reactions of benzo[b]thiophene 1, 1-dioxide [3], and the attempts to prepare the aforementioned sulfoximide analogue of benzo[b]thiophene, also in order to investigate its possible activities in cycloaddition reactions. We have succeeded in preparing the sulfimide derivative, but many attempts to prepare the sulfoximide analogue were so far unsuccessful [4]. Now, we wish to report on the synthesis of the first sulfoximide derivative of benzo[b]thiophene. We will describe our approaches and the route that includes the oxidation of the sulfimide into sulfoximide using the H2O2-P2O5 reagent [5]. Our first results are also showing that the new heterocyclic sulfoximide may be a dipolarophile in cycloadditions, thus, affording new tricyclic sulfoximides.

sulfimides; sulfoximide; benzo(b)thiophene; oxidation

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