March 3, 2026Open Access

Chemodivergent Synthesis of 1,4-Benzo b dithiins and 1,4-Benzodithiafulvenes

Key Points

The synthesis leads to distinct products based on solvent choice—1,4-benzodithiins or 1,4-benzodithiafulvenes.
In DMF, six-membered 1,4-dithiins are formed, while DMSO promotes ring contraction to 1,4-benzodithiafulvenes.
Studies reveal that the balance of S2-/S3•- species and base strength in the solvent influences product outcomes.
Base-promoted reaction mechanisms highlight the complexity and variability in synthetic chemistry pathways.

Abstract

We report a chemodivergent synthesis of 1,4-benzobdithiins and 1,4-benzodithiafulvenes from 2-iodoaryl alkynyl sulfides using a NaSH·xH2O/KOH system. In DMF, the reaction affords six-membered 1,4-dithiins, whereas in DMSO, these intermediates undergo a base-promoted ring contraction to the corresponding 1,4-dithiafulvenes. Photophysical and mass spectrometry studies support the idea that this chemodivergence arises from the interplay between S2-/S3• - equilibrium and base availability in each solvent, which governs whether the 1,4-dithiin framework is preserved or undergoes ring contraction to 1,4-benzodithiafulvenes.

Chemodivergent Synthesis of 1,4-Benzo b dithiins and 1,4-Benzodithiafulvenes

Key Points

Abstract

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