HCTU

HCTU

Names
IUPAC name O-(1H-6-Chlorobenzotriazole-1-yl)-1,1,3,3-tetramethyluronium hexafluorophosphate
Other names 2-(6-Chloro-1H-benzotriazole-1-yl)-1,1,3,3-tetramethylaminium hexafluorophosphate
Identifiers
CAS Number	330645-87-9
3D model (JSmol)	Interactive image
ChemSpider	17339147
ECHA InfoCard	100.116.975
EC Number	608-825-3
PubChem CID	42624899
CompTox Dashboard (EPA)	DTXSID00655231
InChI InChI=1S/C11H15ClN5O.F6P/c1-15(2)11(16(3)4)18-17-10-7-8(12)5-6-9(10)13-14-17;1-7(2,3,4,5)6/h5-7H,1-4H3;/q+1;-1 Key: ZHHGTMQHUWDEJF-UHFFFAOYSA-N
SMILES CN(C)C(=[N+](C)C)ON1C2=C(C=CC(=C2)Cl)N=N1.F[P-](F)(F)(F)(F)F
Properties
Chemical formula	C11H15ClF6N5OP
Molar mass	413.69 g·mol−1
Appearance	White to off white powder
Melting point	>185 °C
Hazards
GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H228, H302, H315, H319, H335
Precautionary statements	P210, P240, P241, P261, P264, P270, P271, P280, P301+P312, P302+P352, P304+P340, P305+P351+P338, P312, P321, P330, P332+P313, P337+P313, P362, P370+P378, P403+P233, P405, P501
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

HCTU is an amidinium coupling reagent used in peptide synthesis. It is analogous to HBTU. ^[1] The HOBt moiety has a chlorine in the 6 position which improves reaction rates and the synthesis of difficult couplings ^{[2] [3]} HCTU and related reagents containing the 6-chloro-1-hydroxybenzotriazole moiety can be prepared by reaction with TCFH under basic conditions. ^[4] It can exist in an N-form (guanidinium) or an O-form (uronium), but the N-form is generally considered to be more stable for this class of reagent. ^[5] In vivo dermal sensitization studies according to OECD 429 confirmed HCTU is a strong skin sensitizer, showing a response at 0.50 wt% in the Local Lymph Node Assay (LLNA) placing it in Globally Harmonized System of Classification and Labelling of Chemicals (GHS) Dermal Sensitization Category 1A. ^[6]

References

1. Marder, Oleg; Shvo, Youval; Albericio, Fernando (2003-08-12). "HCTU and TCTU: New Coupling Reagents — Development and Industrial Aspects". ChemInform. 34 (32). doi:10.1002/chin.200332258. ISSN   1522-2667.
2. Hood, Christina A.; Fuentes, German; Patel, Hirendra; Page, Karen; Menakuru, Mahendra; Park, Jae H. (2008-01-01). "Fast conventional Fmoc solid-phase peptide synthesis with HCTU". Journal of Peptide Science. 14 (1): 97–101. CiteSeerX   10.1.1.595.917 . doi:10.1002/psc.921. ISSN   1099-1387. PMID   17890639. S2CID   24163278.
3. Sabatino, Giuseppina; Mulinacci, Barbara; Alcaro, Maria C.; Chelli, Mario; Rovero, Paolo; Papini, Anna M. (2002-03-01). "Assessment of new 6-Cl-HOBt based coupling reagents for peptide synthesis. Part 1: Coupling efficiency study". Letters in Peptide Science. 9 (2–3): 119–123. doi:10.1007/bf02576873. ISSN   0929-5666. S2CID   29545816.
4. El-Faham, Ayman; Albericio, Fernando (2008-04-01). "Morpholine-Based Immonium and Halogenoamidinium Salts as Coupling Reagents in Peptide Synthesis 1" . The Journal of Organic Chemistry. 73 (7): 2731–2737. doi:10.1021/jo702622c. ISSN   0022-3263. PMID   18321124.
5. Carpino, Louis A.; Imazumi, Hideko; El-Faham, Ayman; Ferrer, Fernando J.; Zhang, Chongwu; Lee, Yunsub; Foxman, Bruce M.; Henklein, Peter; Hanay, Christiane; Mügge, Clemens; Wenschuh, Holger; Klose, Jana; Beyermann, Michael; Bienert, Michael (2002-02-01). "The Uronium/Guanidinium Peptide Coupling Reagents: Finally the True Uronium Salts" . Angewandte Chemie International Edition. 41 (3): 441–445. doi:10.1002/1521-3773(20020201)41:3<441::AID-ANIE441>3.0.CO;2-N. PMID   12491372.
6. Graham, Jessica C.; Trejo-Martin, Alejandra; Chilton, Martyn L.; Kostal, Jakub; Bercu, Joel; Beutner, Gregory L.; Bruen, Uma S.; Dolan, David G.; Gomez, Stephen; Hillegass, Jedd; Nicolette, John; Schmitz, Matthew (2022-06-20). "An Evaluation of the Occupational Health Hazards of Peptide Couplers". Chemical Research in Toxicology. 35 (6): 1011–1022. doi:10.1021/acs.chemrestox.2c00031. ISSN   0893-228X. PMC   9214767 . PMID   35532537.