Developing organoboranes as phase transfer catalysts for nucleophilic fluorination using CsF

Abstract

Despite the general high fluorophilicity of boron, organoboranes such as BEt3 and 3,5-(CF3)2C6H3–BPin are shown herein for the first time, to our knowledge, to be effective (solid to solution) phase-transfer...

Predicting Lewis Acidity: Machine Learning the Fluoride Ion Affinity of p‐Block‐Atom‐Based Molecules

“…Our model correctly labeled BPh 3 as relatively strong and Ph‐BPin ( B in Figure 8) as a relatively weak Lewis acid on the FIA scale. Both are outside of the desired FIA span and accordingly, were found to give poor experimental results [4] . The FIA solv values of two of the most effective phase transfer catalysts, BEt 3 and 3,5‐(CF 3 ) 2 C 6 H 3 ‐BPin ( A in Figure 8) were predicted with high accuracy by the model.…”

“…Both are outside of the desired FIA span and accordingly, were found to give poor experimental results. [4] The FIA solv values of two of the most effective phase transfer catalysts, BEt 3 and 3,5-(CF 3 ) 2 C 6 H 3 -BPin (A in Figure 8) were predicted with high accuracy by the model. Importantly, FIA-GNN coped well with the difference between 40 % substrate conversion after 24 hours and 99 % conversion after 8 hours being less than 20 kJ mol À 1 on the FIA solv scale.…”

Deoxyfluorination of 1°, 2°, and 3° Alcohols by Nonbasic O–H Activation and Lewis Acid-Catalyzed Fluoride Shuttling

“…Under these conditions, the desired deoxyfluorination pathway was favored over the formation of the combined elimination side products 3a′ (5.8:1 ratio of 3a : 3a′ ). The product selectivity for deoxyfluorination could be improved if stoichiometric Ph 3 CBF 4 was replaced by 1.05 equiv of the soluble fluoride ion donor triphenylmethyl fluoride (Ph 3 CF) and a catalytic quantity of BF 3 ·OEt 2 (5 mol %), effectively generating the Ph 3 C + electrophile and BF 4 – nucleophile in situ. , By this Lewis acid-catalyzed “fluoride shuttling” approach, alkylfluoride (±)-3a was formed in 83% yield and 8.3:1 selectivity in favor of deoxyfluorination over elimination (entry 2) . Examining the effect of catalyst stoichiometry, the yield of the desired deoxyfluorinated product was unaffected across a range of loadings; however, the selectivity between fluorinated and eliminated products decreased with increasing catalyst loading (entries 2–5).…”

“…18,19 By this Lewis acid-catalyzed "fluoride shuttling" approach, 20 alkylfluoride (±)-3a was formed in 83% yield and 8.3:1 selectivity in favor of deoxyfluorination over elimination (entry 2). 21 Examining the effect of catalyst stoichiometry, the yield of the desired deoxyfluorinated product was unaffected across a range of loadings; however, the selectivity between fluorinated and eliminated products decreased with increasing catalyst loading (entries 2−5).…”

Activation of fluoride anion as nucleophile in water with data-guided surfactant selection

“…20 While the nucleophilicity of uoride anion in organic solvent is much improved, the high lattice energy of readily available inorganic uorides means that their solubility is oen very low in these solvents. Previous solutions for this conundrum included the use of phase transfer catalyst and water/organic solvent combinations, [46][47][48] and elaborate uoride reagent such as NMe 4 F and NMe 4 F$tAmyl-OH, 19 which have better solubility in organic solvents, or SuFEx reagents, 49 which generate in situ uoride anion in organic solvents. An alternative, yet unexplored, solution is to modify the environment around the uoride anion, and thus its reactivity, at the organic/ water interface through the use of surfactant (Fig.…”