Preparation of New Dialkyl Benzene-, Biphenyl-, and Naphthalene-bis(α-oxoethanedithioates)

Abstract

Novel arene-bis- and -tris(α-oxoethanedithioate) esters of the benzene, the biphenyl, and, in particular, the naphthalene series were prepared by reaction of the corresponding diazoacetyl or bromoacetyl derivatives with elemental sulfur in the presence of triethylamine in dry DMF, and subsequent direct alkylation of the produced dithiocarboxylate anions. The thiolation reaction of the diazoketones was significantly promoted by the addition of anhydrous calcium chloride (calcium chloride–activated thiolation, or CAT). Certain carbonyl-activated methylene and methyl compounds exhibiting no bromo or diazo substituents could be also transformed into dithioesters by the CAT reaction. The structure of three dithioesters was corroborated by X-ray structural analyses.

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Keywords:

• Alkyl β-aryl-α-oxo-ethanedithioates
• α-bromoketones
• calcium chloride activation
• α-diazoketones
• thiolation

Acknowledgments

The Universität Hamburg, the Konrad-Adenauer-Stiftung (graduate scholarship A. S.), and the Fonds der Chemischen Industrie are gratefully acknowledged for financial support. We thank Prof. Dr. U. Behrens (X-Ray), Dr. Volker Sinnwell (NMR), and Manfred Didschun (preparations), Universität Hamburg, for their competent assistance.