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.

Base-Catalyzed Transesterification of Thionoesters

“…Curiously, while the synthesis of thioamides from thionoesters has been reported extensively, the use of alcohols as nucleophiles for the transesterification of thionoesters is extremely rare. − Early research involving transesterification of dithiobenzoyl acetic acid suggested to us that transesterification should provide a straightforward means to rapidly diversify thionoesters. , In addition, exchange reactions with dithioesters and alcohols have been reported. , It was also demonstrated that α-oxo-dithioesters will undergo transesterification yielding thionoesters. , One notable use of this strategy is in the total synthesis of clostrubin, where the resulting thionoester was used in a Barton-Kellogg olefination as a key step in the synthesis …”

“…23,24 It was also demonstrated that α-oxo-dithioesters will undergo transesterification yielding thionoesters. 16,25 One notable use of this strategy is in the total synthesis of clostrubin, where the resulting thionoester was used in a Barton-Kellogg olefination as a key step in the synthesis. 26 Considering the above, we envisioned a streamlined synthesis of structurally diverse thionoesters could be achieved through a straightforward transesterification reaction from a starting methyl thionoester.…”

Tandem SN2 Nucleophilic Substitution/Phospho-Dieckmann Reaction: One-Step Synthesis of 2-Phosphonyl-3-hydroxybenzo[b]thiophenes

“…However, all of these methods have been focused on constructing C2-carbon-substituted benzo­[ b ]­thiophenes. The reports on the synthesis of 3-hydroxybenzo­[ b ]­thiophene substituted by heteroatoms at the C2 position are limited to sulfur and nitrogen substitutions …”