Synthesis and Structural Investigation of Internally Coordinated α-Amidoboronic Acids

Abstract

[structure: see text] Six new N-acyl-boroGly derivatives, along with their N-acyl-boroSar analogues, have been synthesized by modification of conventional procedures. Structural characterization of these alpha-amidoboronic acids was accomplished by extensive use of 11B and 1H NMR spectroscopy. These compounds were prepared to determine the extent of intramolecular B-O dative bond formation within the context of a five-membered (:O=C-N-C-B) ring motif. It is shown that the formation of such dative bonds depends on the nature of the substituents at both the acyl carbon and the nitrogen atoms. Computational evidence from second-order Møller-Plesset perturbation theory is provided in support of these findings.

Development of Boronic Acid Grafted Random Copolymer Sensing Fluid for Continuous Glucose Monitoring

“…However, similar interaction seems weaker between weak Lewis base of amide nitrogen and boron, likely due to the weaker electron donating effect of amide nitrogen 47,48. Therefore, it is more likely that sugar binding was augmented by the interaction involving the carbonyl oxygen coordination to the boron open shell as in ortho -carbonyl oxygen and boron,36,37 in addition to hydrogen bond formation between the N-H group and the oxygen on the boronic acid moiety, which were observed in aliphatic amidoboronic acids 49…”

Computational Insight Into the Enantioselectivity of Homoboroproline Catalyzed Asymmetric Aldol Reaction

“…The analogous structural differences reported by Sakata and Fujimoto in the reaction of allylboronate with benzaldehyde are in line with our results. Another study by Lai et al . on α‐amidoboronic acids provides both experimental and computational evidence that the formation of dative‐bond between carbonyl oxygen and boron plays a catalytic role in enhancing the rate of amide hydrolysis, which also supports our hypothesis.…”

Chemistry of α‐Aminoboronic Acids and their Derivatives

“…The racemic boraalanine (46) (amidomethyl)-boronic (47) acid was synthesized from dibutyl (iodomethyl)boronate and LiHMDS followed by benzoylation [47]. The product from reaction with sodiobenzamide was the imido ester isomer (48) [36].…”

“…The reaction of (1-iodo-2-phenylethyl)-boronate (32) with aqueous ammonia gave 2-phenylethylamine (Scheme 4.7) [39]. N-Acyl-boroGly and N-acyl-boroSar derivatives (33)(34)(35)(36)(37)(38)(39)(40)(41)(42)(43)(44) were recently synthesized (Scheme 4.8) [46]. Structural characterization of these a-amidoboronic acids was accomplished by extensive use of 11 B-and 1 H-nuclear magnetic resonance (NMR) spectroscopy.…”