The Photochemistry of Boron Compounds

Pelter, Andrew; Pardasani, R. T.; Pardasani, P.

doi:10.1016/s0040-4020(00)00533-0

Cited by 58 publications

(30 citation statements)

References 126 publications

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“…Zuschriften lowest excited singlet states (S 2 )w ere conducted at the B3LYP/6-31G(d) level of theory.T he geometry optimization on S 0 at the UB3LYP/6-31G(d) level of theory afforded two electronic structures for the transition state (TS) of the [1,6]H-shift, that is,a no pen-shell TS(OS)a nd ac losed-shell singlet state TS(CS), which lead to the H-shifted biradical (5aCC)a nd zwitterionic (5a +À )i ntermediates,r espectively, prior to the formation of the spirocyclic product 4a (Figure 4; see Figure S3). Thee nergies of the geometries of these intermediates relative to the optimized geometry of 3a in S 0 are + 56.1 kcal mol À1 [TS(OS)], + 68.0 kcal mol À1 [TS-(CS)], + 44.3 kcal mol À1 (5aCC), + 53.8 kcal mol À1 (5a +À ), and + 12.5 kcal mol À1 (4a).…”

Section: Angewandte Chemiementioning

confidence: 99%

“…These findings suggest the spontaneous formation of 4a even in the ground state,once 5a is produced. Moreover,S 1 and S 0 seem to form an unavoidable crossing in the vicinity of TS(CS)o wing to the nonadiabatic coupling between the two states.O verall, the photoinduced cyclization likely proceeds through a [ 1,6]Hshift in S 1 ,followed by anonadiabatic transition from S 1 to S 0 to produce 5a +À ,and aspontaneous CÀCbond formation via either 5a +À or 5aCC in S 0 to afford 4a (Scheme 1). In the early reaction stage,near the Franck-Condon state for 3a,S 1 and S 2 are energetically comparable.Incontrast, the S 2 potential energy surface for the H-shift from 3a to TS is significantly less favorable (ca.…”

Section: Angewandte Chemiementioning

confidence: 99%

“…[1] Acrucial point for the understanding of the reactivity of organoboranes is the isosterism with their carbon congeners (Figures 1a,b). [1] Acrucial point for the understanding of the reactivity of organoboranes is the isosterism with their carbon congeners (Figures 1a,b).…”

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confidence: 99%

“…[2][3][4] Wang and co-workers have recently applied this type of reaction to develop ap hotochromic system. This reaction likely involves a [ 1,6]-sigmatropic hydrogen rearrangement, which should result from as ignificant contribution of the vacant p orbital of the boron atom. [6][7][8] We have recently reported isosteric reactivity for at riorganoborane and its cationic carbon congener.S pecifically,t he 9-dimesitylboryl-substituted dibenzoborepin 1 underwent an isomerization to the borata-allyl product 2 upon photoirradiation, [9] ar eaction which can be regarded as ab ora-Nazarov cyclization (Figure 1c).…”

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confidence: 99%

“…Energy profiles of S 0 ,S 1 ,and S 2 for the[1,6]H-shifto f3a, calculated at the B3LYP/6-31G(d) level of theory.All energy values are relative to that of 3a.F or the energy profiles of the transformation of 3a into 5aCC (S 0 ), the relative energies from 3a to TS(CS), and TS(OS) to 5aCC correspond to the closed-shell and open-shellsinglet states, respectively.…”

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Photochemical Intramolecular C−H Addition of Dimesityl(hetero)arylboranes through a [1,6]‐Sigmatropic Rearrangement

et al. 2017

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A new reaction mode for triarylboranes under photochemical conditions was discovered. Photoirradiation of dimesitylboryl-substituted (hetero)arenes produced spirocyclic boraindanes, where one of the C-H bonds in the ortho-methyl groups of the mesityl substituents was formally added in a syn fashion to a C-C double bond of the (hetero)aryl group. Quantum chemical calculations and laser flash photolysis measurements indicated that the reaction proceeds through a [1,6]-sigmatropic rearrangement. This behavior is reminiscent of the photochemical reaction mode of arylalkenylketones, thus demonstrating the isosteric relation between tricoordinate organoboron compounds and the corresponding pseudo-carbocationic species in terms of pericyclic reactions. Despite the disrupted π-conjugation, the resulting spirocyclic boraindanes exhibited a characteristic absorption band at relatively long wavelengths (λ=370-400 nm).

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Section: Angewandte Chemiementioning

confidence: 99%

Section: Angewandte Chemiementioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Photochemical Intramolecular C−H Addition of Dimesityl(hetero)arylboranes through a [1,6]‐Sigmatropic Rearrangement

et al. 2017

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Boron: Organoboranes

Jï¿1⁄2ï¿1⁄2kle¹

2005

Encyclopedia of Inorganic Chemistry

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This chapter provides an overview of recent developments in the highly interdisciplinary field of organoboron chemistry. The most important routes for the synthesis of organoboranes via transmetallation, hydroboration and other boration reactions, as well as CH activation are outlined. The various classes of organoboranes thus accessible are presented according to the nature of the organic substituents. Special emphasis is given to applications of organoboranes. For example, the development of new chiral organoboranes that are commonly used in enantioselective synthesis is shown. Moreover, the importance of fluorinated arylboranes as highly efficient Lewis acid catalysts and cocatalysts for organic transformations and polymerization reactions is discussed. The use of triarylboranes and related compounds as electronic and optical materials for device applications, and as sensors for the recognition of anions and neutral Lewis bases is also described in detail.

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Photochemical Transformations Involving Organoboron

Mellerup

Wang

2019

Patai's Chemistry of Functional Groups

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Boron gets its name from the term borax, the mineral from which it was originally isolated, by analogy with carbon due to their chemical similarities. Unlike its neighbor on the periodic table, however, boron only possesses enough valence electrons to form three covalent bonds. This means that organoboron compounds are inherently electron deficient and typically adopt a trigonal‐planar (sp 2 ‐hybridized) geometry with the empty p z orbital of boron lying orthogonal to the bonding plane. In this form, boron is isoelectronic and isostructural with a positively charged carbocation, which gives rise to many of the applications often associated with trivalent organoboranes (e.g., organic synthons and electron‐transport materials). Coordinatively saturating these systems with anionic or neutral Lewis bases yields tetrahedral, four‐coordinated boron compounds with a formal negative charge. This new bonding arrangement significantly alters the orbital composition of the resulting molecules, imparting new features such as intense charge transfer (CT) luminescence and, in some cases, unique photochemical reactivities such as photochromism or photoelimination. This chapter will document recent progress in photochemical transformation based on organoboron compounds. A brief overview of concepts related to photophysical and photochemical processes will be presented, followed by an introduction to photochromic systems and a comprehensive review of organoboron photochemistry. Several recently discovered classes of photoresponsive organoboron molecules and their potential applications will be presented.

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The Photochemistry of Boron Compounds

Cited by 58 publications

References 126 publications

Photochemical Intramolecular C−H Addition of Dimesityl(hetero)arylboranes through a [1,6]‐Sigmatropic Rearrangement

Photochemical Intramolecular C−H Addition of Dimesityl(hetero)arylboranes through a [1,6]‐Sigmatropic Rearrangement

Boron: Organoboranes

Photochemical Transformations Involving Organoboron

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