Mild copper-catalyzed trifluoromethylation of terminal alkynes using an electrophilic trifluoromethylating reagent

A catalytic process for trifluoromethylation of terminal alkynes with Togni’s reagent has been developed, affording trifluoromethylated acetylenes in good to excellent yields. The reaction is conducted at room temperature and exhibits tolerance to a range of functional groups.     

Copper-catalyzed trifluoromethylation of aryl and vinyl boronic acids with an electrophilic trifluoromethylating reagent

A copper-catalyzed trifluoromethylation of aryl- and alkenylboronic acids with Togni's reagent was described. The reaction proceeded in good to excellent yields for a range of different substrates including heteroarylboronic acids and substrates with a variety of functional groups under mild reaction conditions.     

Enantioselective nickel-catalyzed cross-coupling reactions of trialkynylindium reagents with racemic secondary benzyl bromides

The first enantioselective sp-sp3 cross-coupling reaction between alkynyl organometals and racemic benzyl bromides is reported. The coupling is performed at room temperature by using NiBr2diglyme and (S)-(iPr)-Pybox as the catalytic system and trialkynylindium reagents as nucleophiles. The reaction is stereoconvergent, both enantiomers of the racemic benzyl bromide are converted into one enantiomer of the product, and stereospecific. The reaction takes place efficiently in good yields and with high atom economy, as the triorganoindium reagents transfer the three organic groups attached to indium (only 40 mol % of R3In is used).     

Some studies on nucleophilic trifluoromethylation using the shelf-stable trifluoromethylacetophenone-N,N-dimethyltrimethylsilylamine adduct

The simple thermal addition product of N,N-dimethyltrimethylsilylamine with 2,2,2-trifluoroacetophenone provides a shelf-stable reagent for nucleophilic trifluoromethylation of both the carbonyl and the imine group.     

Mild electrophilic trifluoromethylation of secondary and primary aryl- and alkylphosphines using hypervalent iodine(iii)-CF(3) reagents

A direct, mild and efficient trifluoromethylation of primary and secondary phosphines is achieved with easily accessible, cheap hypervalent iodine compounds acting as electrophilic CF(3)-transfer reagents.     

Ordering the relative power of electrophilic fluorinating,trifluoromethylating, and trifluoromethylthiolating reagents: A summary of recent efforts

Electrophilic fluorination and fluoroalkylation are one of the most promising and efficient strategies in the synthesis of organofluorine compounds. The rapid progress of this field has been made possible by the emergence of a wide variety of power-variable, readily prepared, and easy-to-handle electrophilic fluorinating and fluoroalkylating reagents. Understanding the relative power of these reagents is thus vital for their use in synthetic transformations. This digest will outline some recent efforts to quantitatively ordering the relative power of electrophilic fluorinating, trifluoromethylating, and trifluoromethylthiolating reagents.     

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.     

New hypervalent iodine reagents for electrophilic trifluoromethylation and their precursors: synthesis, structure, and reactivity

Several new five- and a six-membered heterocyclic monochloroiodanes, including two cationic species, were synthesized. Three of which were used for the preparation of corresponding trifluoromethylation reagents. These compounds were characterized by X-ray crystallography for a comparative structural study. A reactivity study on the trifluoromethylation of para-toluenesulfonic acid has been conducted in order to compare initial rates. Compounds having a longer I-O bond display a higher reactivity.     

Polarography of polyhalogen-substituted benzyl bromides and the corresponding benzylmercuric bromides

Conclusions On the basis of a comparison of the polarographic behavior of a series of polybromine-substituted benzylmercuric bromides and the corresponding substituted benzyl bromides it was shown in the case of benzyl bromides active in the preparative reaction with metallic mercury that the reduction takes place through the initial formation of organomercury compounds at the surface of the mercury electrode.Translated from Izvestiya Akademii Nauk SSSR. Seriya Khimicheskaya, No. 3, pp. 546–548, March, 1985.     

Nucleophilic and electrophilic substitutions of difluoropropargyl bromides

Fundamental organic reactions like nucleophilic and electrophilic substitutions have seldom been studied on fluorinated propargyl or allenyl modules, when the carbon atom undergoing substitution is bonded to two fluorine atoms. Herein we report a practical synthesis of difluoropropargyl bromides from substituted acetylenes and dibromodifluorometane using a wide variety of alkyl, aryl or silyl substrates. The synthesis of O-, S- and carboxylic acid derivatives of difluoropropargyl bromide is also described. These compounds are suitable starting materials for the synthesis of electrophilically substituted difluoropropargyl derivatives via magnesium and fluoride promoted reactions. An indium-mediated reaction of silyldifluoropropargyl bromide, followed by electrophilic trapping with bromine led to a very useful bromoallene, which was then used in reactions with nucleophiles (C, O, N, P, S, Hal) to yield a de facto bimolecular nucleophilic substitution of a difluoropropargyl bromide.     

Yttrium triflate-catalyzed efficient chemoselective S-benzylation of indoline-2-thiones using benzyl alcohols

A highly efficient yttrium triflate-catalyzed chemoselective S-benzylation of indolin-2-thiones using variously substituted benzyl alcohols has been developed for the synthesis of indole-based sulfides. This procedure presents a greener approach for the synthesis of S-alkylated indoles. The reaction condition is amenable to primary, secondary, and tertiary benzylic alcohols as the benzyl group donors.     

Regioselective electrophilic trifluoromethylation of substituted anilines and derivatives in superacid

In a one pot procedure, treatment of chloro or methyl substituted acetanilides in HF/SbF₅/CCl₄ followed by addition of HF/pyridine yields trifluoromethyl derivatives with high regioselectivity.     

Reaction of N-alkylglycolurils with electrophilic reagents

The N-hydroxymethylation, N-acetylation, and N-acetoxymethylation of mono-, di-, and trialkylglycolurils by reaction with the electrophilic reagents formaldehyde and acetaldehyde have been studied. General methods have been developed for the preparation of mono-, di-, and tri-N-hydroxymethylglycolurils by treatment of differently substituted N-alkylglycolurils with formaldehyde (as hemiformal in methanol) and the synthesis of di-N-and tri-N-acetyl-or N-acetoxymethylglycolurils via the electrophilic substitution of hydrogen atoms for an acetyl group at the nitrogen or oxygen atoms in the hydroxymethyl groups of glycolurils using acetic anhydride. The regioselectivity of the reaction of the 2-t-Bu-and 2-c-C₆H₁₁-glycolurils with formaldehyde has been shown to yield a 4,6-di(hydroxymethyl) derivative. It was found that the hydroxymethylation of 2,4-and 2,6-dialkylglycolurils occurs regioselectively with a stoichiometric ratio of glycoluril to hemiformal and permits preparation of their mono-and dihydroxymethyl derivatives. The enantiomeric analysis of the obtained compounds has been carried out for the first time using HPLC on chiral phases. X-ray analysis has been carried out on the previously unreported racemic 2,6-diacetoxymethyl-4,8-dimethylglycoluril. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 411–423, March, 2006.     

Copper-free asymmetric allylic alkylation using grignard reagents on bifunctional allylic bromides

A series of substrates containing a vinylic bromide were employed in a copper-free methodology using bidendate NHC ligands. The desired compounds are generally obtained with good enantioselectivity and good regioselectivity. Importantly the copper-catalyzed system afforded a lower enantioselectivity value. The catalytic products could be transformed into a broad scope of new 1,1-disubstituted olefins in a single step transformation without erosion of the enantioselectivity.     

Copper-catalyzed electrophilic amination of diorganozinc reagents

The copper-catalyzed electrophilic amination of diorganozinc reagents employing O-acyl N,N-dialkyl hydroxylamine derivatives as aminating agents is described. This reaction offers a general method for the preparation of tertiary amines in high yields and is noteworthy for its convenience both in terms of reaction conditions employed (room temperature, 相似文献   

Regioselective electrophilic trifluoromethylation of indolines, oxindoles and indoles in superacid

Treatment of indolines and N-acylindoles with HF/SbF₅/CCl₄ yields 6-trifluoro derivatives (indole numbering) whereas indoles and oxindoles give the 5-trifluoro derivatives in good yield.