Boron Reagents and Catalysts for the Functionalization of Strained Heterocycles

Abstract

The particular nature of boron compounds allows an ample modularity of their properties ranging from Lewis acids, C‐nucleophiles, B‐nucleophiles, or even conjunctive reagents for new synthetic manipulations. Moreover, the increasing demand for functionalized boron derivatives for pharmaceutical or material science applications requires the development of new synthetic methods for boron introduction in organic compounds. This review summarizes the possible combinations of boron derivatives with a variety of strained heterocycles reported in the most recent literature.

N‐Heterocycle‐Editing to Access Fused‐BN‐Heterocycles via Ring‐Opening/C−H Borylation/Reductive C−B Bond Formation

“…The intermolecular coupling of B−Br bond with tributylethynylstannane suggests that Ni(0) preferentially activates B−Br over C sp 3 ‐Br (Figure 4F). On the basis of the above experiments and the previous literature reports, [8c,11g,13,15,16] we propose a plausible mechanism for the tandem reaction (Figure 4G): the complex of 1‐(2‐vinylphenyl)azetidine and BBr 3 undergoes ring‐opening to obtain the Int‐I , [11g] which sequentially proceeds intramolecular nucleophilic attack, cyclization, and proton elimination to afford Int‐II [15] . Oxidative addition of B−Br bond in Int‐II to Ni 0 species affords Int‐III , [13] which is reduced by Zn to give a B−Ni I species Int‐IV .…”

Distinct electronic effects of borane– and boryl–nickel complexes for catalyzing H2 activation

“…6 Due to their strong electrophilic characteristic, organoboron reagents are commonly regarded as Lewis acids for participating in reactions. 7 For instance, BX 3 (X = F, Cl, Br), a neutral boron reagent, can promote regioselective ring-opening reactions (Fig. 1a).…”

Copper-Catalyzed Ring-Opening Reactions of Alkyl Aziridines with B2pin2: Experimental and Computational Studies

“…The ring-opening (RO) reactions of aziridines with nucleophilic reagents are important operations in synthetic organic chemistry to obtain β-substituted amines [ 1 , 2 , 3 , 4 ]. Beside the consolidated use of heteroatom- and carbon-based nucleophiles, the use of nucleophilic boron reagents in the RO of strained three-membered heterocycles has come to the fore more recently [ 5 , 6 , 7 , 8 ]. The regio- and stereoselective introduction of a boron atom in sp 3 -rich functionalized molecules is of particular importance in synthetic organic chemistry, considering that the boron atom is easily transformable into hydroxy, amino or halo groups or it can serve as cross-coupling partner [ 9 ].…”