Hypervalent Iodine Trifluoromethylation Research Articles

General Reaction Mode of Hypervalent Iodine Trifluoromethylation Reagent: A Density Functional Theory Study

The mechanisms of trifluoromethylation with hypervalent iodine trifluoromethylation reagent (Togni’s reagent 1) have been comprehensively studied by density functional theory (DFT) calculations. The results show that there are two general reaction modes for reagent 1: (I) Mode-A, acting as a CF3• free radical source. When one-electron reductants are available in the reaction system, such as CuI, FeII, TEMPONa, or electron-rich lithium enolate, 1 will be reduced via single-electron transfer (SET) and give out CF3• free radical concertedly. In the CuI-catalyzed trifluoromethylation of terminal olefins, CuI promotes the homo-cleavage of the F3C–I bond in 1 via SET to produce CuII species and CF3• free radical. Then the CF3• free radical attacks the olefin, leading to trifluoromethyl alkyl radical intermediate. Subsequently, the CuII species act as a one-electron oxidant oxidizing the alkyl radical to carbocation intermediate, and the following deprotonation leads to the final product. Other mechanisms, such as formation of F3C–CuIII species via oxidative addition, formation of allylic radical intermediate, were considered and excluded. (II) Mode-B, acting as a CF3+ cation source. 1 can be activated by a Lewis acid such as ZnII and becomes more inclined to undergo an SN2 type nucleophilic attack at the CF3 group by nucleophiles (pentanol in this work). For substrates studied in this paper, such as the lithium enolate, pentanol, and sodium 2,4,6-trimethylphenolate, the competition between their reducibility and nucleophilicity determines the reaction mode of regent 1.

ChemInform Abstract: In situ Generation of PhI+CF3 and Transition‐Metal‐Free Oxidative sp2 C—H Trifluoromethylation.

AbstractBy simple mixing of PhI(OAc)2, TmsCF3 and KF, a hypervalent iodine trifluoromethylating species is formed and directly applied in sp2 C—H trifluoromethylation reactions of ketene dithioacetals and indoles.

Reactivity of an electrophilic hypervalent iodine trifluoromethylation reagent with hydrogen phosphates—A mechanistic study

The electrophilic trifluoromethylation of hydrogen phosphates with the reagent trifluoromethyl-1,3-dihydro-3,3-dimethyl-1,2-benziodoxole (1) was studied by means of initial rates determined for pseudo first order setups and subsequent Taft analysis of the calculated relative rates. A positive polar sensitivity factor, indicative of a negative charge forming during the rate-determining step, was found for the whole data set.

Electrophilic trifluoromethylation of arenes and N-heteroarenes using hypervalent iodine reagents

The reaction of hypervalent iodine trifluoromethylating reagents with a variety of arenes and N-heteroarenes gives access to the corresponding trifluoromethylated compounds. In comparative studies, 1-trifluoromethyl-1,3-dihydro-3,3-dimethyl-1,2-benziodoxole ( 2) proved to be the superior to 1-trifluoromethyl-1,2-benziodoxol-3-( 1H)-one ( 1) for the direct aromatic trifluoromethylation. Depending on the individual substrates, additives such as zinc bis(trifluoromethylsulfonyl)imide or tris(trimethylsilyl)silyl chloride proved helpful in promoting the reactions. In the case of nitrogen heterocycles a pronounced tendency for the incorporation of the trifluoromethyl group at the position adjacent to nitrogen was observed.

Electrophilic Trifluoromethylation of Primary Phosphines: Synthesis of a P-Bis(trifluoromethyl) Derivative of BINAP

The new chiral diphosphine ligand (R)-(2′-(bis(trifluoromethyl)phosphino)-1,1′-binaphthyl-2-yl)diphenylphosphine (2), which contains a bis(trifluoromethyl)phosphine group, was prepared in five steps from (R)-BINOL (5). As a key transformation, the unprecedented electrophilic double trifluoromethylation of the primary phosphine 8 was achieved using the hypervalent iodine trifluoromethylation reagent 1-trifluoromethyl-1,2-benziodoxol-3-(1H)-one (1), derived from o-iodobenzoic acid. The palladium dichloride complex of this ligand (10) shows the P(CF3)2 group with a high degree of pyramidalization at the P atom and a relatively short Pd−P bond (2.2230(4) Å), both features being indicative of the strong s-character of the phosphorus lone pair.

ChemInform Abstract: Acid‐Mediated Formation of Trifluoromethyl Sulfonates from Sulfonic Acids and a Hypervalent Iodine Trifluoromethylating Agent.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Reactivity of a Hypervalent Iodine Trifluoromethylating Reagent toward THF: Ring Opening and Formation of Trifluoromethyl Ethers

1-Trifluoromethyl-1,2-benziodoxol-3-(1H)-one (1) is able to transfer the electrophilic CF(3) group to the oxygen atom of THF in the presence of a Lewis or Bronsted acid. This results in a new ring-opening reaction of THF yielding trifluoromethyl ethers. Details of this reaction and the insight gained into the mechanism of action of reagent 1 are reported.

ChemInform Abstract: Zinc‐Mediated Formation of Trifluoromethyl Ethers from Alcohols and Hypervalent Iodine Trifluoromethylation Reagents.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Zinc‐Mediated Formation of Trifluoromethyl Ethers from Alcohols and Hypervalent Iodine Trifluoromethylation Reagents

AbstractSchieb mal rüber: Der Transfer einer intakten Trifluormethylgruppe von einem hypervalenten Iodreagens zu einem aliphatischen Alkohol verläuft glatt bei einer Aktivierung durch Zinkbis(triflimid). Dies ist eine einfache Methode zur Synthese von Trifluormethoxyalkyl‐Derivaten, die sonst nur schwer zugänglich sind.magnified image

Zinc‐Mediated Formation of Trifluoromethyl Ethers from Alcohols and Hypervalent Iodine Trifluoromethylation Reagents

A (fluor)ry of activity: The transfer of an intact trifluoromethyl group from a hypervalent iodine reagent to an aliphatic alcohol occurs smoothly upon activation by zinc bis(triflimide). This constitutes a straightforward method for the preparation of trifluoromethoxy alkyl derivatives, compounds otherwise difficult to access.

ChemInform Abstract: Reactivity of a 10‐I‐3 Hypervalent Iodine Trifluoromethylation Reagent with Phenols.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Acid-mediated formation of trifluoromethyl sulfonates from sulfonic acids and a hypervalent iodine trifluoromethylating agent

A variety of sulfonic acids have been trifluoromethylated using 1-trifluoromethyl-1,2-benziodoxol-3(1H)-one under mild conditions in good to excellent yields. Initial mechanistic investigations of this reaction show a clean second-order kinetics and only very weak substrate electronic effects.

Reactivity of a 10-I-3 Hypervalent Iodine Trifluoromethylation Reagent With Phenols

The reaction of the 10-I-3 hypervalent iodine electrophilic trifluoromethylation reagent 1-trifluoromethyl-1,2-benziodoxol-3-(1H)-one (2) with 2,4,6-trimethylphenol, after deprotonation with NaH and in the presence of 18-crown-6 in a polar, nonprotic solvent, affords 1,3,5-trimethyl-2-(trifluoromethoxy)benzene (4) only as a byproduct. Trifluoromethylation occurs preferentially at the ortho- and para-positions of the aromatic core, giving the corresponding trifluoromethylcyclohexadienones 5 and 6. In case the ortho- and/or para-positions are not substituted, the corresponding products of an aromatic, electrophilic substitution are obtained in moderate yield, for example, 2-trifluoromethyl-4-tert-butylphenol (10a) from 4-tert-butylphenol (10).