Detailed Mechanistic Pattern in Halogen Dance Reactions of Iodothiophenes

Background: Synthetic chemists have utilized base catalyzed halogen dance reactions ever since their discovery by Bunnet et al. Many modifications under various conditions have enabled synthetic chemists to build substituted heterocyclic targets with rich structural diversity. Methods: Using DFT-Cam-B3LYP/ land2dz computations and focusing on Hannes Frohlich et al. Halogen dance reactions of iodothiophenes, a new iodo-bridged transition state is proposed. This iodo- bridged TS was then used to put forth 8 possible isomerization as well as 8 possible disproportionation paths. Results & Discussion: All mechanistic pathways were then thoroughly investigated based on TS’s energy and protonation/deprotonation steps to find the most suitable pathways. Collectively, these mechanistic pathways were joined like a jigsaw puzzle to yield, for the first time, a comprehensive cascade-like pattern for base-catalyzed halogen dance in iodothiophenes. Conclusion: The present work may shed light on a dynamic domino mechanism that may well dominate the organic chemistry of iodothiophenyl anions. Trends like this may reveal mechanistic pathways in base digestion of halogenated aromatic compounds in CS2.