Biphasic catalysis acylation

Fluorous biphase catalysis was also applied in Friedel-Crafts acylation with Yb tris(perfluoroalkanesulfonyl)methide catalysts with acid anhydrides.59 Of the aromatics studied, activated compounds and naphthalene (95% conversion) showed satisfactory reactivity. 

A second example of latent biphasic catalysis used the polymer-bound trifunctional base catalyst 129 as a dimethylaminopyridine analog in acylation of 2,6-dialkylphenols by (Boc)20 in a 1 1 heptane-ethanol solvent mixture. After acylation of the phenol was complete, the addition of 10 vol% H2O perturbed the system. The yields of product carbonate from Eq. 66 were 35,66,89,99%, 99, and 99% through the first six cycles. 

A second example of latent biphasic catalysis used the polymer-bound trifunctional base catalyst 129 as a dimethylaminopyridine analog in acylation of... 

Activation of the carboxylic acid as the acyl chloride permits direct reaction with azide anion to form the acyl azide substrates for Curtius rearrangement. Sodium azide is commonly used, and the reaction has been used on the process chemistry scale for the synthesis of benzyl-A-vinyl carbamate. Acryloyl chloride was combined with sodium azide in a biphasic system with phase-transfer catalysis (PTC), providing acyl azide 25. Upon heating, Curtius rearrangement provided vinyl isocyanate, which was distilled directly into benzyl alcohol containing phenothiazine (27) to inhibit polymerization of 26 and triethylamine to catalyze addition of the alcohol to the isocyanate. The vinyl carbamate product 28 was isolated by crystallization. As the autiior clearly pointed out, preparation and reaction of acyl azides, particularly on large scales, require appropriate safety precautions. 

---