A General Method for Imine Formation Using B(OCH₂CF₃)₃

Abstract

Tris(2,2,2-trifluoroethyl)borate [B(OCH2CF3)3] was found to be a mild and general reagent for the formation of a variety of imines by condensation of amides or amines with carbonyl compounds. N-Sulfinyl, N-toluenesulfonyl, N-(dimethylamino)sulfamoyl, N-diphenylphosphinoyl, N-(α-methylbenzyl), and N-(4-methoxyphenyl) aldimines are all accessible using this reagent at room temperature. The reactions are operationally simple, and the products are obtained without special workup or isolation procedures.

Protecting‐Group‐Free Amidation of Amino Acids using Lewis Acid Catalysts

“…Given that B(OCH 2 CF 3 ) 3 has previously been shown to promote imine formation when used stoichiometrically, we also explored a one‐pot unprotected amino acid amidation/condensation reaction to provide access to imidazolidinones in a single step (Scheme ). In this case the cyclisation reaction was much quicker (1–2 h), and yielded products with very little or no signs of racemization.…”

“…Given that B(OCH 2 CF 3 ) 3 has previously been shown to promote imine formation when used stoichiometrically, [31] we also explored aone-pot unprotectedamino acid amidation/condensation reactiont op rovide access to imidazolidinones in as ingle step (Scheme 7). In this case the cyclisation reactionw as much quicker (1-2 h), and yieldedp roducts with very little or no signs of racemization.I midazolidinones derived from as election of amino acids (Phe, Ala and Sar) were cyclized with aliphatic (12 c,d, 12 g-i, 12 k), benzylic (12 a), heterocyclic (12 b, 12 j)a nd hydroxyl containing (12 a)a ldehydes or ketones in good to excellenty ields.…”

Versatile Organic Chemistry on Vanadium‐Based Multi‐Electron Reservoirs

“…The amino compound 2 c could successfully be post‐functionalized with aromatic aldehydes in tetrahydrofuran at 60 °C to the corresponding imines (Scheme ). B(OCH 2 CF 3 ) 3 was used as coupling reagent . Again, redox behavior and solubility were retained.…”

“…B(OCH 2 CF 3 ) 3 was used as coupling reagent. [46] Again, redox behavior and solubility were retained. By using 2-pyridylaldehyde, 3,5-di-tert-butyl-2hydroxyaldehyde, or 4-nitrobenzaldehyde to form Schiff bases with 2c,b identate arrangements were introduced to the aggregates (Figure 4).…”

Ruthenium‐Catalyzed Aerobic Oxidation of Amines

“…[26] Traditionally,i mines are prepared by the condensationo f amines with carbonyl compounds, especially unstablea ldehydes, and dehydrating agentsa sw ell as Lewis acid catalysts are required in many cases (Scheme 3). [27] In this regard, synthesis of imines and nitriles by oxidative dehydrogenation (ODH) of aminesprovides abetter alternative as it avoids the use of toxic reagents. Although, this method was previously reported by using stoichiometric inorganic [28] or iodine-based oxidants, [29] dehydrogenation of amines in the presenceo ft ransition-metalc atalysts and O 2 has emerged as one of the attractive methods for the preparation of nitriles and imines (Scheme4).…”