Direct Episulfidation of Alkenes and Allenes with Elemental Sulfur and Thiiranes as Sulfur Sources, Catalyzed by Molybdenum Oxo Complexes

Abstract

The molybdenum oxo complexes 1a and 1b catalyze efficiently the sulfur transfer to a series of alkenes 4 and allenes 6, for which elemental sulfur, phenylthiirane, or methylthiirane have been employed as sulfur sources to afford the corresponding episulfides 5 and 7. The most effective catalytic episulfidation system to date is the combination of the dithiophosphate-ligated oxo complex 1b and phenylthiirane (Ibeta). This metathesis process is efficient enough to convert usually reluctant alkenes (cyclopentene, cycloheptene, Z-cyclooctene, Z-cyclononene, E-cyclodecene, norbornene, and even bicyclopropylidene) to their episulfides in good yields under mild conditions. The direct catalytic sulfuration of allenes (cyclonona-1,2-diene, cyclonona-1,2,5-triene, cyclodeca-1,2-diene, and 2,4-dimethylpenta-2,3-diene) to their labile methylenethiiranes is unprecedented.

Catalytic Isofunctional Reactions—Expanding the Repertoire of Shuttle and Metathesis Reactions

“…[68] They identified phenylthiirane to be ap roductive sulfenium donor and they were able to effect the episulfidation of arange of cyclic E-and Zalkenes by using Mo complex 41.A llenes also proved amenable to episulfidation under these reaction conditions. [68] They identified phenylthiirane to be ap roductive sulfenium donor and they were able to effect the episulfidation of arange of cyclic E-and Zalkenes by using Mo complex 41.A llenes also proved amenable to episulfidation under these reaction conditions.…”

Shuttle Catalysis—New Strategies in Organic Synthesis

“…The work discussed hereu nderlines the potential of shuttle catalysis for the generation of reactive functionality from widelya vailableunsaturated systems. [27,28] An advantageo fthis approachi st hat the reactive functionality is transferred from ad onor molecule and complements existing methodologies. Another benefiti st he broad reactivity profile of the products of the transfer process that enables numerous different functional groups to be introduced thusl eadingt oag eneral approach for the functionalization of unsaturated systems.…”

Three‐Membered Heterocycles. Structure and Reactivity

“…The dithiophosphate molybdenum complex 668 actually catalyzes the transfer of sulfur from one episulfide to another alkene. This allows the use of a more readily available substrate (e.g., 659) as a sulfur donor, as shown in the episulfidation of transcyclononene 669 [694]. Thiatriazole 671 also functions as a stoichiometric sulfur transfer reagent for a wide range of alkene substrates (e.g., 672 !…”