Teoc Protecting Group

05 February, 2019 / by SK / in Reactions

11467

Overall Score4

Generality
Orthogonality to Other PGs
Criteria #3
Criteria #4
Criteria #5

General Characteristics

2-(Trimethylsilyl)ethoxycarbonyl (Teoc) group is one of commonly used carbamate protecting groups for amines. It is stable towards hydrolysis and other nucleophilic attacks, and tolerates most acidic and reductive conditions, including heterogeneous hydrogenation. Deprotection is most commonly performed by treatment with fluoride reagents such as TBAF.

General References

Teoc-OSu: Shute, R. E.; Rich, D. H. Synthesis 1987, 346. DOI: 10.1055/s-1987-27939
Teoc-NTShimizu, M.; Sodeoka, M. Org. Lett. 2007, 9, 5231. DOI: 10.1021/ol7024108

Reaction Mechanism

Protection

N-[2-(trimethylsilyl)ethoxycarbonyloxy]succinimide (Teoc-OSu) is the commonly used reagent to protect amines as Teoc carbamates. Bases such as pyridine or triethylamine are normally used. The Schotten-Baumann conditions, in which inorganic bases are used, are also viable for protecting amino acids.

Deprotection

Similar to other silyl-based protecting groups, Teoc can be deprotected using fluoride ion. The attack of fluoride to the silicon atom leads to β-elimination and decarboxylation, releasing the free amine along with ethylene, carbon dioxide, and Me₃SiF.

Examples

The Sodeoka reagent (Teoc-NT) is useful to protect amines since the nitrotriazole byproduct is insoluble and can be removed by filtration alone.^[1]