Togni reagent II

Togni reagent II
Names
	Preferred IUPAC name 1-(Trifluoromethyl)-1λ3,2-benziodoxol-3(1H)-one
	Other names Togni's reagent II; Togni reagent 2
Identifiers
CAS Number	887144-94-7 ;
3D model (JSmol)	Interactive image;
ChemSpider	24807962 ;
PubChem CID	24850981;
UNII	DHY074A7WG;
CompTox Dashboard (EPA)	DTXSID10647708;
	InChI InChI=1S/C8H4F3IO2/c9-8(10,11)12-6-4-2-1-3-5(6)7(13)14-12/h1-4H Key: XHEOXSQMBWJOKP-UHFFFAOYSA-N;
	SMILES C1=CC=C2C(=C1)C(=O)OI2C(F)(F)F;
Properties
Chemical formula	C8H4F3IO2
Molar mass	316.018 g·mol−1
Appearance	colorless crystalline solid
Melting point	122.4–123.4 °C (252.3–254.1 °F; 395.5–396.5 K)
Solubility in water	soluble in methylene chloride, chloroform, acetonitrile, methanol, ethanol, acetone
Hazards
GHS pictograms
GHS Signal word	Warning
GHS hazard statements	H315, H319, H335
GHS precautionary statements	P261, P264, P271, P280, P302+352, P304+340, P305+351+338, P312, P321, P332+313, P337+313, P362, P403+233, P405, P501
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
	Infobox references

Togni reagent II (1-trifluoromethyl-1,2-benziodoxol-3(1H)-one) is a chemical compound used in organic synthesis for direct electrophilic trifluoromethylation.^[1]^[2]

History

Synthesis, properties, and reactivity of the compound were first described in 2006 by Antonio Togni and his coworkers at ETH Zurich.^[3] The article also contains information on Togni reagent I (1,3-dihydro-3,3-dimethyl-1-(trifluoromethyl)-1,2-benziodoxole).

Preparation

The synthesis consists of three steps. In the first step, 2-iodobenzoic acid is oxidized by sodium periodate and cyclized to 1-hydroxy-1,2-benziodoxol-3(1H)-one. The target compound can then be obtained by acylation with acetic anhydride and subsequent substitution reaction with trifluoromethyltrimethylsilane.^[4]

Alternatively, trichloroisocyanuric acid can be used as oxidant in the place of sodium periodate for a newer one-pot synthesis method.^[5]

Properties

Physical properties

The compound crystallized in a monoclinic crystal structure. The space group is P2₁/n with four molecules in the unit cell.^[3] From the crystallographic data, a density of 2.365 g·cm⁻³ was deduced.^[3]

Chemical properties

Pure Togni reagent II is metastable at room temperature. Heating it above the melting point will lead to strong exothermic decomposition, in which trifluoroiodomethane (CF₃I) is released.^[4] The heat of composition at a temperature of 149 °C and higher has been determined to be 502 J·g⁻¹.^[6] From recrystallization in acetonitrile, small amounts of trifluoromethyl-2-iodobenzoate and 2-iodobenzyl fluoride were observed as decomposition products.^[4] Togni reagent II reacts violently with strong bases and acids, as well as reductants.^[4] In tetrahydrofuran, the compound polymerizes.^[4]

Uses

Togni reagent II is used for trifluoromethylation of organic compounds. For phenolates, the substitution takes place preferably in the ortho position. It is possible to obtain a second substitution by using an excess of Togni reagent II.^[7]

Reactions with alcohols yield the corresponding trifluoromethyl ethers.^[8]

Trifluoromethylation of alkenes is possible under copper catalysis.^[9]

References

↑ PubChem. "1-(Trifluoromethyl)-1,2-benziodoxol-3(1H)-one". National Center for Biotechnology Information. https://pubchem.ncbi.nlm.nih.gov/compound/24850981.
↑ Kieltsch, Iris; Eisenberger, Patrick; Stanek, Kyrill; Togni, Antonio (2008-04-30). "Recent Advances in Electrophilic CF3-Transfer Using Hypervalent Iodine(III) Reagents" (in en). Chimia International Journal for Chemistry 62 (4): 260–263. doi:10.2533/chimia.2008.260. http://openurl.ingenta.com/content/xref?genre=article&issn=0009-4293&volume=62&issue=4&spage=260.
↑ ^3.0 ^3.1 ^3.2 Eisenberger, Patrick; Gischig, Sebastian; Togni, Antonio (2006-03-08). "Novel 10-I-3 Hypervalent Iodine-Based Compounds for Electrophilic Trifluoromethylation" (in en). Chemistry - A European Journal 12 (9): 2579–2586. doi:10.1002/chem.200501052. ISSN 0947-6539. PMID 16402401.
↑ ^4.0 ^4.1 ^4.2 ^4.3 ^4.4 Stanek, Kyrill; Koller, Raffael; Kieltsch, Iris; Eisenberger, Patrick; Togni, Antonio (2009-09-15), John Wiley & Sons, Ltd, ed. (in en), 1-(Trifluoromethyl)-1,2-benziodoxol-3(1 H )-one, John Wiley & Sons, Ltd, pp. rn01121, doi:10.1002/047084289x.rn01121, ISBN 978-0-471-93623-7
↑ Matoušek, Václav; Pietrasiak, Ewa; Schwenk, Rino; Togni, Antonio (2013-07-05). "One-Pot Synthesis of Hypervalent Iodine Reagents for Electrophilic Trifluoromethylation" (in en). The Journal of Organic Chemistry 78 (13): 6763–6768. doi:10.1021/jo400774u. ISSN 0022-3263. PMID 23734560.
↑ Fiederling, Nikolaus; Haller, Jan; Schramm, Heiko (2013-03-15). "Notification about the Explosive Properties of Togni's Reagent II and One of Its Precursors" (in en). Organic Process Research & Development 17 (3): 318–319. doi:10.1021/op400035b. ISSN 1083-6160.
↑ Stanek, Kyrill; Koller, Raffael; Togni, Antonio (2008-10-03). "Reactivity of a 10-I-3 Hypervalent Iodine Trifluoromethylation Reagent With Phenols" (in en). The Journal of Organic Chemistry 73 (19): 7678–7685. doi:10.1021/jo8014825. ISSN 0022-3263. PMID 18771328.
↑ Koller, Raffael; Stanek, Kyrill; Stolz, Daniel; Aardoom, Raphael; Niedermann, Katrin; Togni, Antonio (2009-06-02). "Zinc-Mediated Formation of Trifluoromethyl Ethers from Alcohols and Hypervalent Iodine Trifluoromethylation Reagents" (in en). Angewandte Chemie 121 (24): 4396–4400. doi:10.1002/ange.200900974.
↑ Parsons, Andrew T.; Buchwald, Stephen L. (2011-09-19). "Copper-Catalyzed Trifluoromethylation of Unactivated Olefins" (in en). Angewandte Chemie 123 (39): 9286–9289. doi:10.1002/ange.201104053. PMID 21919144.

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[1] PubChem. "1-(Trifluoromethyl)-1,2-benziodoxol-3(1H)-one". National Center for Biotechnology Information. https://pubchem.ncbi.nlm.nih.gov/compound/24850981.

[2] Kieltsch, Iris; Eisenberger, Patrick; Stanek, Kyrill; Togni, Antonio (2008-04-30). "Recent Advances in Electrophilic CF3-Transfer Using Hypervalent Iodine(III) Reagents" (in en). Chimia International Journal for Chemistry 62 (4): 260–263. doi:10.2533/chimia.2008.260. http://openurl.ingenta.com/content/xref?genre=article&issn=0009-4293&volume=62&issue=4&spage=260.

[:1-3] 3.0 ^3.1 ^3.2 Eisenberger, Patrick; Gischig, Sebastian; Togni, Antonio (2006-03-08). "Novel 10-I-3 Hypervalent Iodine-Based Compounds for Electrophilic Trifluoromethylation" (in en). Chemistry - A European Journal 12 (9): 2579–2586. doi:10.1002/chem.200501052. ISSN 0947-6539. PMID 16402401.

[:0-4] 4.0 ^4.1 ^4.2 ^4.3 ^4.4 Stanek, Kyrill; Koller, Raffael; Kieltsch, Iris; Eisenberger, Patrick; Togni, Antonio (2009-09-15), John Wiley & Sons, Ltd, ed. (in en), 1-(Trifluoromethyl)-1,2-benziodoxol-3(1 H )-one, John Wiley & Sons, Ltd, pp. rn01121, doi:10.1002/047084289x.rn01121, ISBN 978-0-471-93623-7

[5] Matoušek, Václav; Pietrasiak, Ewa; Schwenk, Rino; Togni, Antonio (2013-07-05). "One-Pot Synthesis of Hypervalent Iodine Reagents for Electrophilic Trifluoromethylation" (in en). The Journal of Organic Chemistry 78 (13): 6763–6768. doi:10.1021/jo400774u. ISSN 0022-3263. PMID 23734560.

[6] Fiederling, Nikolaus; Haller, Jan; Schramm, Heiko (2013-03-15). "Notification about the Explosive Properties of Togni's Reagent II and One of Its Precursors" (in en). Organic Process Research & Development 17 (3): 318–319. doi:10.1021/op400035b. ISSN 1083-6160.

[7] Stanek, Kyrill; Koller, Raffael; Togni, Antonio (2008-10-03). "Reactivity of a 10-I-3 Hypervalent Iodine Trifluoromethylation Reagent With Phenols" (in en). The Journal of Organic Chemistry 73 (19): 7678–7685. doi:10.1021/jo8014825. ISSN 0022-3263. PMID 18771328.

[8] Koller, Raffael; Stanek, Kyrill; Stolz, Daniel; Aardoom, Raphael; Niedermann, Katrin; Togni, Antonio (2009-06-02). "Zinc-Mediated Formation of Trifluoromethyl Ethers from Alcohols and Hypervalent Iodine Trifluoromethylation Reagents" (in en). Angewandte Chemie 121 (24): 4396–4400. doi:10.1002/ange.200900974.

[9] Parsons, Andrew T.; Buchwald, Stephen L. (2011-09-19). "Copper-Catalyzed Trifluoromethylation of Unactivated Olefins" (in en). Angewandte Chemie 123 (39): 9286–9289. doi:10.1002/ange.201104053. PMID 21919144.

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