Lead-Catalyzed Aqueous Benzoylation of Carbohydrates with an Acyl Phosphate Ester

Abstract

Biochemical systems utilize adenylates of amino acids to aminoacylate the 3'-terminal diols of tRNAs. The reactive acyl group of the biological acylation agent is a subset of the general class of acyl phosphate monoesters. Those compounds are relatively stable in aqueous solutions, and their alkyl esters are conveniently prepared. It has previously been shown that biomimetic reactions of acyl phosphate monoesters with diols and carbohydrates are promoted by lanthanide salts. However, they also promote hydrolysis of acyl phosphate reagents, and the overall yields are modest. An assessment of the catalytic potential of alternative Lewis acids reveals that lead ions may be more effective as catalysts than lanthanides. Treatment of carbohydrates with benzoyl methyl phosphate (BMP) and triethylamine in water with added lead nitrate produces monobenzoyl esters in up to 75% yield. This provides a water-compatible pathway for novel patterns of benzoylation of polyhydroxylic compounds.

Benzoxaborole Catalyst for Site‐Selective Modification of Polyols

“…Accordingly, a polyol modification that tolerates aqueous media is a desirable synthetic strategy. Recently, the well‐designed acylation and glycosylation of carbohydrates in aqueous media have been reported. We thus postulated that carbohydrate modification in water could be enabled by benzoxaborole, due to its outstanding cis‐1,2‐diol affinity and activation.…”

Metal-Catalyzed Site-Selective Monoacylation of Diols in Aqueous Media

“…This led us to examine the utility of lead salts and zinc salts. 44 Persson and coworkers had reported an in-depth study of coordination of lead ions in oxygen donor solvents. 45 We examined the effectiveness of lead ions as catalysts for acylation of a dCA and AMP by phenylalanine ethyl phosphate (PheEtP).…”

“…46 We assume that similar mechanisms apply for the three metals with yields affected by metal-diol affinity and the effectiveness of Lewis acid catalysis in the acyl transfer step. 44 The values of t 1/2 for the hydrolysis of phenylalanyl ethyl phosphate (PheEtP) at 4 °C in the presence of zinc or lead salts are 60 and 5 minutes, respectively. 47 The reaction in the presence of Cu 3+ salts is not effective as it selectively promotes the hydrolysis of PheEtP.…”

Chemistry Takes a Bath: Reactions in Aqueous Media

“…36−41 These reports also highlight how aqueous reactions facilitate the synthesis and modification of highly hydrophilic compounds, such as amino acids, 40 peptides, 42 and carbohydrates. 43 But in addition to synthesis, we also find papers focused on biology, including bioorthogonal reactions 44−47 and characterization of therapeutic compounds, 48 thus attesting to the diversity of topics in this compendium dedicated to "Chemistry in Water", as illustrated on the cover of this thematic issue.…”

“…In this special issue of The Journal of Organic Chemistry , there are 30 articles describing research that reflects a variety of modern advancements, all realized in aqueous media. Synthesis is the aim of most of the papers, which include sustainable methodology, − asymmetric catalysis, “on-water” chemistry, , micelle-enabled reactions, − heterogeneous catalysis, − electro- and photochemistry, , and reactions mediated by enzymes. − These reports also highlight how aqueous reactions facilitate the synthesis and modification of highly hydrophilic compounds, such as amino acids, peptides, and carbohydrates . But in addition to synthesis, we also find papers focused on biology, including bio-orthogonal reactions − and characterization of therapeutic compounds, thus attesting to the diversity of topics in this compendium dedicated to “Chemistry in Water”, as illustrated on the cover of this thematic issue.…”