Ring Expansion, Photoisomerization, and Retrocyclization of 1,4,2‐Diazaboroles

Su, Bochao; Li, Yongxin; Ganguly, Rakesh; Kinjo, Rei

doi:10.1002/anie.201708720

Cited by 16 publications

(6 citation statements)

References 123 publications

(33 reference statements)

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“…On the other hand, a similar reaction of the imino- N -heterocyclic carbene ligand with MesBBr 2 and subsequent reduction with an excess of KC 8 produced a B , N -dihydroindole derivative 342 as a white solid in 72% yield (Scheme ). They have proved that the formation of 342 from 341 proceeds via the intermediacy of the B -bromo-analogue of 1,4,2-diazaborole 340 .…”

Section: Nhc Complexes Of Main Group Elementsmentioning

confidence: 99%

NHCs in Main Group Chemistry

et al. 2018

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Since the discovery of the first stable N-heterocyclic carbene (NHC) in the beginning of the 1990s, these divalent carbon species have become a common and available class of compounds, which have found numerous applications in academic and industrial research. Their important role as two-electron donor ligands, especially in transition metal chemistry and catalysis, is difficult to overestimate. In the past decade, there has been tremendous research attention given to the chemistry of low-coordinate main group element compounds. Significant progress has been achieved in stabilization and isolation of such species as Lewis acid/base adducts with highly tunable NHC ligands. This has allowed investigation of numerous novel types of compounds with unique electronic structures and opened new opportunities in the rational design of novel organic catalysts and materials. This Review gives a general overview of this research, basic synthetic approaches, key features of NHC-main group element adducts, and might be useful for the broad research community.

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Section: Nhc Complexes Of Main Group Elementsmentioning

confidence: 99%

NHCs in Main Group Chemistry

et al. 2018

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“…Thep air of bulky Fmes groups at boron and the remaining Xyl aryl group at nitrogen are oriented close to perpendicular to the core.T he B1-N2-B2 subunit is delocalized (B1ÀN2:1 .420(2) ,N 2 ÀB2:1 .440( 2) )a si st he opposite N1-C2-C3 enamine unit (C2ÀC3:1 .337(2) ,N 1 À C2:1.371( 2) ). Consequently,the central connecting N2ÀC2 linkage is long at 1.440 (2) .…”

Section: Methodsmentioning

confidence: 99%

“…Kinjo et al described the first derivatives of this rare class of compounds in 2015. [2] They prepared them starting from the imino-functionalized N-heterocyclic carbene precursors 1.T othe best of our knowledge,n oa dditional principal entry into this class of aromatic five-membered BNN heterocycles has been reported. We have now developed anew pathway to examples of the dihydro-1,4,2-diazaborole family and to the oxygen and sulfur analogues (4,5), the BN isosteres of furan and thiophen, and even of the BN indolizine derivative 6 (see Scheme 1).…”

Section: Introductionmentioning

confidence: 99%

Three‐Component Reaction to 1,4,2‐Diazaborole‐Type Heteroarene Systems

Erker

Daniliuc

et al. 2021

Angewandte Chemie

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The borane FmesBH 2 reacts in at hree-component reaction with an isonitrile and asmall series of organonitriles to give rare examples of the class of dihydro-1,4,2-diazaborole derivatives.I narelated way,a nnulated BN-indolizine derivatives became conveniently available,a sw ere dihydro-1,4,2oxaza-or thiazaborole derivatives.T he nucleophilic framework of ad ihydro-1,4,2-diazaborole example allowed for an uncatalyzed acylation reaction. It also served as a1 ,3-dipolar reagent and underwent a[ 3 + +2] cycloaddition/[4+ +2] cycloreversion sequence when treated with methyl propiolate to give the respective pyrrole product. The [3+ +2] cycloaddition product of ad ihydro-1,4,2-diazaborole derivative with Nphenylmaleimide was isolated and its heterobicyclo-[2.2.1]heptane derived structure characterized by X-ray diffraction.

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“…Until now, very limited methods have implemented this process (Figure 1B). [8] In 2017, Kinjo and co‐workers reported that the insertion of extremely active bromoborylene (BrB:) into the C−N bond achieved N ‐heterocycle enlargement [8a] . In 2019, Yorimitsu's group achieved skeletal editing of indoles to 1,2‐benzazaborines through indole reductive ring‐opening with lithium metal to form dianionic species and subsequent organoboronic esters trapping [8b] .…”

Section: Figurementioning

confidence: 99%

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

Zhang,

Su,

Guo

et al. 2024

Angew Chem Int Ed

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Skeletal editing of N‐heterocycles has recently received considerable attention, and the introduction of boron atom into heterocycles often results in positive property changes. However, direct enlargement of N‐heterocycles through boron atom insertion is rarely reported in the literature. Here, we report a N‐heterocyclic editing reaction through the combination boron atom insertion and C‐H borylation, accessing the fused BN‐heterocycles. The synthetic potential of this chemistry was demonstrated by substrate scope and late‐stage diversification of products.

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Ring Expansion, Photoisomerization, and Retrocyclization of 1,4,2‐Diazaboroles

Abstract: Diverse skeletal transformations of 1,4,2-diazaboroles through ring expansion, photoisomerization, and retrocyclization led to the isolation of various B,N-dihydroindole (compounds 3 and 6), 1,3-azaborolidin-2-imine (compound 7), and 1,4,2-diazaborol-3-imine derivatives (compound 11).

Cited by 16 publications

References 123 publications

NHCs in Main Group Chemistry

NHCs in Main Group Chemistry

Three‐Component Reaction to 1,4,2‐Diazaborole‐Type Heteroarene Systems

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

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