Template effects and supramolecular control of photoreactions in solution

Bibal, Brigitte; Mongin, Cédric; Bassani, Dario M.

doi:10.1039/c3cs60366k

Cited by 103 publications

(62 citation statements)

References 271 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Since the short excited state lifetime and low activation energy for reaction in excited state leave little room for manipulating the chiral induction, to achieve enantioselectivity one has to ensure that the substrate molecule already resides in a chiral environment during the excitation step. Nevertheless, examples of excited state reactions with high enantioselectivity have been achieved (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13). Recently, a new strategy for high enantioselective photochemical reactions has emerged.…”

Section: Introductionmentioning

confidence: 99%

Chiral Inductions in Excited State Reactions: Photodimerization of Alkyl 2‐Naphthoates as a Model

Tung

Chen

Feng

et al. 2018

Photochem & Photobiology

View full text Add to dashboard Cite

Enantioselectivity in organic transformations continues to be a topic major interest in organic photochemistry. In the last decade, synergistic combination of photocatalysis and organocatalysis has emerged as a powerful strategy to gain enantioselectivity in photochemical reactions, and remarkable achievements have been obtained. In this strategy, the asymmetric induction is provided in ground state. In contrast, in the conventional enantioselective photochemistry, the chiral induction is controlled in electronic excited state, and to achieve high stereoselectivity is still a formidable challenge. Because the reactions of excited states often yield strained products with unique structures in single step that are difficult to form by thermal reactions, the development of new strategies attempted to achieve enantioselectivity in excited state reactions is still highly desired. Since the short excited state lifetime and low activation energy for reaction in excited state leave little room for manipulating the chiral induction, in order to gain enantioselectivity the substrate molecule has to already reside in a chiral environment during the excitation step. Chiral auxiliaries and chiral supramolecular hosts can provide such environments. In this presentation, we summarize the studies employing chiral auxiliary and chiral microreactor approaches to achieve high asymmetric inductions in excited state reactions performed in our laboratory. We chose the photodimerization of alkyl 2-naphthoates as a reaction model to give deeper insights into the basic factors controlling chiral induction in excited state.

show abstract

Section: Introductionmentioning

confidence: 99%

Chiral Inductions in Excited State Reactions: Photodimerization of Alkyl 2‐Naphthoates as a Model

Tung

Chen

Feng

et al. 2018

Photochem & Photobiology

View full text Add to dashboard Cite

show abstract

“…For example, it was demonstrated that the optical properties of organic dyes may be modified drastically upon complexation in the CB cavity [7]. At the same time, this effect of the ligand–CB[ n ] interplay may be used to modify and control the photochemical properties of a guest molecule [8–9]. For instance, the encapsulation of photoactive molecules in the constrained medium of a cucurbituril cavity enables the performance of chemo-, regio- or stereoselective photoreactions that are not possible in homogeneous solution [10–15].…”

Section: Introductionmentioning

confidence: 99%

Interactions between photoacidic 3-hydroxynaphtho[1,2-b]quinolizinium and cucurbit[7]uril: Influence on acidity in the ground and excited state

Becher

Berdnikova

Dzubiel

et al. 2017

Beilstein J. Org. Chem.

View full text Add to dashboard Cite

3-Hydroxynaphtho[1,2-b]quinolizinium was synthesized by cyclodehydration route and its optical properties in different media were investigated. The absorption and emission spectra of this compound depend on the pH of the solution. Thus, at higher pH values the deprotonation yields a merocyanine-type dye that exhibits significantly red-shifted absorption bands and causes a dual emisson, i.e., a combination of emission bands of the hydroxyquinolizinium and its deprotonated form. Whereas this compound is a weak acid in the ground state (pK a = 7.9), it has a strongly increased acidity in the excited state (pK a * = 0.4). As a result, the blue-shifted fluorescence of the hydroxyquinolizinium becomes dominant only under strongly acidic conditions. In addition, it is shown that 3-hydroxynaphtho[1,2-b]quinolizinium binds to cucurbit[7]uril (CB[7]) with moderate affinity (K b = 1.8 × 104 M−1, pH 5) and that the pK a and pK a * values of this ligand increase by about two to three orders of magnitude, respectively, when bound to CB[7].

show abstract

“…8,16 Many reactions of cycloaddition are known in organic chemistry, for instance -[2 + 3] cyloaddition, 47 [3 + 4] cycloaddition, 48 [4 + 2] cycloaddition. Many examples of pre-organized dimeric pairs are described in the literature via the coordination of the initial ethylene systems with metal cations 11,30,32,34,38,40,43,50 or the formation of hydrogen bonds between the components, 7,9,10,12,14,15,17,20,21,[23][24][25]29,30,40,41,46,50 as well as entering two structural units in cavitand cavitycyclodextrins, calixarenes, cucurbit [8]uril, nanocages. Whereas, PCA represents a temperature independent process.…”

Section: Introductionmentioning

confidence: 99%

“…49 However, these reactions are thermal and they proceed in solution. 17,35,36,39,40 Another approach to create the "pre-organized" dimeric pair is only possible for the PCA reaction in the solid state. It is photochemically reversible, often regio-and stereoselective and it proceeds in both solution and in the solid phase.…”

Section: Introductionmentioning

confidence: 99%

Features of styryl dye crystal packings and their influence on [2 + 2] photocycloaddition reaction with single crystal retention

et al. 2015

View full text Add to dashboard Cite

A new styryl dye of the 2-benzothiazole series which contains three methoxy groups and an iodide anion was synthesized. Three triclinic crystal forms of this dye were investigated by single crystal X-ray diffraction.All the modifications were shown to contain centrosymmetrically related stacks of cations with the syn-"head-to-tail" mutual arrangement. Stacks of cations are arranged as dimeric pairs with short interatomic distances between the ethylene group carbon atoms, d 1 = 3.54-3.75 Å and significantly longer analogous distances between the adjacent pairs, d 2 = 4.61-4.68 Å. The main difference of the packing consists in various orientations of N-ethyl substituents with respect to the centre of the dimer. The solid phase [2 + 2] photocycloaddition (PCA) reaction resulting in rctt isomer of the cyclobutane derivative, only proceeds in pairs where N-substituents are oriented outward from the centre of the dimeric pair. PCA is accomplished as a "single crystal-to-single crystal" transformation. CrystEngCommThis journal is

show abstract

Template effects and supramolecular control of photoreactions in solution

Abstract: A review of supramolecular and template effects on photochemical reactions in solution is presented. Photoinduced [2+2] and [4+4] cycloaddition reactions, isomerization, electron transfer and radical processes are covered, as well as examples of DNA photoligation.

Cited by 103 publications

References 271 publications

Chiral Inductions in Excited State Reactions: Photodimerization of Alkyl 2‐Naphthoates as a Model

Chiral Inductions in Excited State Reactions: Photodimerization of Alkyl 2‐Naphthoates as a Model

Interactions between photoacidic 3-hydroxynaphtho[1,2-b]quinolizinium and cucurbit[7]uril: Influence on acidity in the ground and excited state

Features of styryl dye crystal packings and their influence on [2 + 2] photocycloaddition reaction with single crystal retention

Contact Info

Product

Resources

About