Tris(2,2,2-trifluoroethyl) borate, also commonly referred to as the Sheppard amidation reagent, is a chemical compound with the formula B(OCH₂CF₃)₃. This

borate ester In organic chemistry, borate esters are organoboron compounds which are conveniently prepared by the stoichiometric condensation reaction of boric acid with alcohols. There are two main classes of borate esters: orthoborates, and metaborates, . ...

reagent is used in organic synthesis.

Preparation

Tris(2,2,2-trifluoroethyl) borate can be prepared by reaction of

trifluoroethanol 2,2,2-Trifluoroethanol is the organic compound with the formula CF3CH2OH. Also known as TFE or trifluoroethyl alcohol, this colourless, water-miscible liquid has a smell reminiscent of ethanol. Due to the electronegativity of the trifluoromethyl ...

with

boron trichloride Boron trichloride is the inorganic compound with the formula BCl3. This colorless gas is a reagent in organic synthesis. It is highly reactive toward water. Production and structure Boron reacts with halogens to give the corresponding trihalides. ...

borane dimethylsulfide Borane dimethylsulfide (BMS) is a complexed borane reagent that is used for hydroborations and reductions. The advantages of BMS over other borane reagents, such as borane-tetrahydrofuran, are its increased stability and higher solubility. BMS ...

boron tribromide Boron tribromide, BBr3, is a colorless, fuming liquid compound containing boron and bromine. Commercial samples usually are amber to red/brown, due to weak bromine contamination. It is decomposed by water and alcohols. Chemical properties Boron ...

, or

boric anhydride Boron trioxide or diboron trioxide is the oxide of boron with the formula . It is a colorless transparent solid, almost always glassy (amorphous), which can be crystallized only with great difficulty. It is also called boric oxide or boria. It h ...

. The latter is more convenient for larger scale preparations due to its low cost and ease of handling. :CF₃CH₂OH + B₂O₃ → B(OCH₂CF₃)₃ The product is purified by distillation.

Applications

The reagent is mostly used in condensation reactions. It has been shown to promote the direct formation of

amide In organic chemistry, an amide, also known as an organic amide or a carboxamide, is a compound with the general formula , where R, R', and R″ represent organic groups or hydrogen atoms. The amide group is called a peptide bond when it is ...

s from carboxylic acids and amines as well as the formation of

imine In organic chemistry, an imine ( or ) is a functional group or organic compound containing a carbon–nitrogen double bond (). The nitrogen atom can be attached to a hydrogen or an organic group (R). The carbon atom has two additional single bo ...

s from amines or amides with carbonyl compounds. It has also been used for the coupling of unprotected

amino acid Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha am ...

s with amines. It has also been shown to mediate

formylation In biochemistry, the addition of a formyl functional group is termed formylation. A formyl functional group consists of a carbonyl bonded to hydrogen. When attached to an R group, a formyl group is called an aldehyde. Formylation has been identi ...

of amines, via transamidation of

dimethylformamide Dimethylformamide is an organic compound with the formula ( CH3)2NC(O)H. Commonly abbreviated as DMF (although this initialism is sometimes used for dimethylfuran, or dimethyl fumarate), this colourless liquid is miscible with water and the majo ...

. It is a strong Lewis acid (AN = 66, Gutmann-Beckett method).Beckett, Michael A; Rugen-Hankey Martin P; Strickland, Gary C; Varma, K. Sukumar, ''Lewis acidity in haloalkyl orthoborate and metaborate esters'', (2001) ''Phosphorus, Sulfur, and Silicon'', 168, 437-440.

Preparation

Applications

References

Further reading