Synthesis of methyl derivatives of linear and angular thienocoumarins and thiopyranocoumarins

Rodighiero, P.; Pastorini, G.; Chilin, Adriana; Marotto, Annalisa

doi:10.1002/jhet.5570350411

Cited by 26 publications

(8 citation statements)

References 9 publications

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“…56 Similarly, psoralene analogues such as pyrrolocoumarins 57 and thioangelicins 58 were also synthesized starting from the corresponding coumarins. 56 Similarly, psoralene analogues such as pyrrolocoumarins 57 and thioangelicins 58 were also synthesized starting from the corresponding coumarins.…”

Section: Scheme 27 Synthesis Of Psoralenes From 6-hydroxybenzofuransmentioning

confidence: 99%

π-Expanded coumarins: synthesis, optical properties and applications

et al. 2015

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Coumarins fused with other aromatic units have recently emerged as a hot topic of research. Their synthesis is partly based on classical methodologies such as Pechmann reaction or Knoevenagel condensation, but it also sparked the discovery of completely new pathways. In very recent years so-called vertically-expanded coumarins were synthesized, effectively expanding the portfolio of existing architectures. A subtle relationship exists between the structure of fused coumarins and their optical properties. Although absorption of UV-radiation and light is unifying theme among these π-expanded coumarins, the fluorescence properties strongly depend on the structure. The mode of fusion, the type of additional ring and the presence of electron-donating and electron-withdrawing substituents all influence the photophysical parameters. Recent advances made it possible to modulate their absorption from 300 nm to 550 nm, resulting in new coumarins emitting orange light. This review serves as a guide through both synthesis strategies and structure-property relationship nuances. Strong intramolecular charge-transfer character made it possible to reach suitable values of two-photon absorption crosssection. Photophysical advantages of π-expanded coumarins have been already utilized in fluorescence probes and two-photon excited fluorescence microscopy.

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Section: Scheme 27 Synthesis Of Psoralenes From 6-hydroxybenzofuransmentioning

confidence: 99%

π-Expanded coumarins: synthesis, optical properties and applications

et al. 2015

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“…42 Many of the more interesting uses of the NKR have been in accessing novel sulfur-containing heterocycles and their derivatives, such as the thieneocoumarins 28 and 29 and thiopyranocoumarins 30 and 31 which are typical examples ( Figure 2). 43 The more challenging example of substituted 7-hydroxybenzo [b]thiophene and its derivatives was accomplished via NKR, providing sulfur isosteres 32 of biologically active hydroxyindoles (Scheme 18). 44 This approach proceeded through 2-mercapto-3-methoxybenzaldehyde (33) which also provided access to 7-substituted 1,2-benzisothiazoles 34.…”

Section: General Routes To Ar-shmentioning

confidence: 99%

Mechanism and Application of the Newman-Kwart O→S Rearrangement of O-Aryl Thiocarbamates

Lloyd‐Jones¹,

Moseley²,

Renny³

2008

Synthesis

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This literature review focuses on the thermal rearrangement of O-aryl thiocarbamates to yield the corresponding S-aryl thiocarbamates: the Newman-Kwart rearrangement. The purpose of the review is to highlight the utility of the rearrangement which provides a key step in an efficient route to convert phenols into thiophenols. The scope of the Newman-Kwart rearrangement is illustrated by way of numerous examples of its application to the preparation of Ar-S species ranging from large-scale industrial processes through to the synthesis of complex organic molecules such as ligands and supramolecular structures. The review contains 238 references and covers just over 40 years of the literature, from the first reports of the rearrangement by Edwards and Pianka in 1965 up to mid-2007. 1 Introduction 2 The Newman-Kwart Rearrangement (NKR) 2.1 Background and History 2.2 Preparation of O-Aryl Thiocarbamates for NKR and Subsequent Cleavage 2.3 Mechanism of Rearrangement 2.4 Nonclassical Conditions for Rearrangement 2.5 Allylic and Benzylic Rearrangements 2.

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“…In these compounds, the furan intracyclic oxygen was replaced by a sulfur atom. Preliminary results show that these compounds also photobind monofunctionally to DNA with high yield (7) and exhibit strong photobiological activity.…”

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confidence: 94%

Photophysical Behavior of Angelicins and Thioangelicins: Semiempirical Calculations and Experimental Study

et al. 1998

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The decay processes of the lowest excited singlet and triplet states of five methylated angelicins (4,6,4'-trimethylangelicin, MA, and four methylated thioangelicins, MTA; see Scheme 1) were investigated in five solvents by stationary and pulsed fluorometric and flash photolytic techniques. In particular, the solvent effects on absorption, fluorescence, quantum yields of fluorescence (+F) and triplet formation (&), lifetimes of fluorescence ( T~) and the triplet state ( T~) and the quantum yields of singlet oxygen production (+,J were investigated. Semiempirical (ZINDOK-CI) calculations were carried out to obtain information (transition probabilities and nature) on the lowest excited singlet and triplet states. The quantum mechanical calculations and the solvent effect on the photophysical properties showed that the lowest excited singlet state (S,) is a partially allowed n,n* state, while the close-lying S2 state is n,n* in nature. The efficiencies of fluorescence, S, + TI intersystem crossing (ISC) and S1 + So internal conversion (IC) strongly depend on the energy gap between S1 and S2 and are explained in terms of the so-called proximity effect. In fact, for MA in cyclohexane, only the S1 + So internal conversion is operthrough S, -+ So IC only, while in acetonitrile and ethanol, fluorescence and ISC increase significantly. For these compounds there is strong evidence that a '(n,.rr*) state lies just

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Synthesis of methyl derivatives of linear and angular thienocoumarins and thiopyranocoumarins

Cited by 26 publications

References 9 publications

π-Expanded coumarins: synthesis, optical properties and applications

π-Expanded coumarins: synthesis, optical properties and applications

Mechanism and Application of the Newman-Kwart O→S Rearrangement of O-Aryl Thiocarbamates

Photophysical Behavior of Angelicins and Thioangelicins: Semiempirical Calculations and Experimental Study

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