Insight into the Mechanism of Reversible Ring-Opening of 1,3-Benzoxazine with 
Thiols

Urbaniak, Tobias; Soto, Marc; Liebeke, Manuel; Koschek, Katharina

doi:10.1021/acs.joc.6b02727

Item

ITEM ACTIONSEXPORT

Add to Basket

Local TagsRelease HistoryDetailsSummary

Released

Journal Article

Insight into the Mechanism of Reversible Ring-Opening of 1,3-Benzoxazine with Thiols

MPS-Authors

/persons/resource/persons210577

Liebeke, Manuel
Department of Symbiosis, Max Planck Institute for Marine Microbiology, Max Planck Society;

External Resource

No external resources are shared

Fulltext (restricted access)

There are currently no full texts shared for your IP range.

Fulltext (public)

There are no public fulltexts stored in PuRe

Supplementary Material (public)

There is no public supplementary material available

Citation

Urbaniak, T., Soto, M., Liebeke, M., & Koschek, K. (2017). Insight into the Mechanism of Reversible Ring-Opening of 1,3-Benzoxazine with Thiols. JOURNAL OF ORGANIC CHEMISTRY, 82(8), 4050-4055. doi:10.1021/acs.joc.6b02727.

Cite as: https://hdl.handle.net/21.11116/0000-0001-C1CB-0

Abstract

The reversible ring-opening addition and fragmentation reaction of p-cresol-based N-phenylbenzoxazine with aliphatic and aromatic thiols was investigated in solvent mediated and solvent-free reactions. Independently of the used thiol, N-phenylbenzoxazine and the thiols reacted to equilibrium with comparable amounts of reactants and products in aprotic solvent, whereas in protic solvent almost full conversions were reached. In contrast, thiol reactivity was a crucial factor in solvent-free reactions yielding fast and complete conversions for a more acidic thiol and balanced equilibrium concentrations in case of thiols with high pK(a) values. The strong influence of thiols with low pKa values emphasizes the relevance of the protonation step in the ring opening reactions of 1,3-benzoxazines with thiols in absence of solvents where acidity predominates nucleophilicity. The reverse reactions, namely adduct dissociation and benzoxazine recovery, were successfully conducted at elevated temperatures and reduced pressure facilitated by the removal of the formed thiols yielding up to 95% recovered 1,3-benzoxazine. These results provide deeper understanding of the reversible ring-opening reaction mechanism of 1,3-benzoxazine with thiols.