Synthesis of Acylboron Compounds

Abstract

Acylboron compounds are emerging as versatile functional groups with applications in multiple research fields. Their synthesis, however, is still challenging and requires innovative methods. This Minireview provides an overview on the obstacles of acylboron synthesis and highlights notable advances within the last three years on new strategies to overcome the challenges posed by the formation of acyl–boron bonds.

Formyl MIDA Boronate: C1 Building Block Enables Straightforward Access to α‐Functionalized Organoboron Derivatives

“…Theorigin of strikingly different stability of formyl MIDA boronate 1 and its previously described analogue 5 (which was even characterized crystallographically) is of particular interest. Similar values of 13 CNMR chemical shifts of the carbonyl groups of 1 (235.6 ppm in CD 3 CN-[D 6 ]DMSO (9:1)) and 5 (233.1 ppm in CD 2 Cl 2 ) [30] indicate that the electronic effects of the corresponding boron-containing substituents might be more or less similar. Therefore,w es uggest that the main cause of the remarkable stability of 5 as compared to MIDA boronate 1 is the increased steric hindrance introduced by the C 6 F 5 and pyridine substituents at B-atom which presumably shield carbonyl group from the nucleophilic attack and prevent spontaneous polymerization (see Figure S1 for the X-ray structure of 5).…”

“…[3][4][5][6][7][8][9][10][11][12] Among the mentioned boron-containing structural motifs, acylboron derivatives (Scheme 1B)a re known to be an emerging class of compounds with strong potential for novel synthetic applications. [13] Thef irst characterized acylboranes contained either adiamine ligand coordinated to the B-atom (type a) [14][15][16] or an N-heterocyclic carbene (type b). [17] Development of acyltrifluoroborate reagents (type c) [18,19] was another important contribution which allowed to elaborate anew method of amide-forming ligation.…”

Recent Advances in the Synthesis of Acylboranes and Their Widening Applicability

“…However, they have now become a recognized and highly useful compound class. 30 Their potential as reagents for amide-forming ligation is immense, as proven by the research highlighted here. The sheer ubiquity of the amide bond in nature means that this reaction could be used in almost every setting.…”

Boron-promoted Deprotonative Conjugate Addition: Development of Geminal diborons as Versatile Soft Pronucleophiles and Acyl An-ion Equivalents

“…The unique chemical reactivity and applications of acylborons in organic synthesis and bioconjugation have inspired several creative synthetic methods. 25,26 While the α-keto 27 and β-keto acylborons 28 can be prepared using several approaches, methods to access γ-keto acylborons are scarce. 29 Inspired by our recently developed route to MIDA acylborons, 15,16 the geminal diboron motif in the conjugate addition product 3y (Scheme 4) was successfully transformed into the unsymmetrical diboron 6.…”