Synthesis of 3-Substituted Isocoumarins via a Cascade Intramolecular Ullmann-Type Coupling–Rearrangement Process

In this paper, we describe the use of p‐TSA based Deep Eutectic Solvents (DESs) as alternative environmental‐friendly “active” solvents for the microwave‐mediated synthesis of 6‐substituted 3,4‐fused 2‐pyranones, and in particular isocoumarins, starting from 2‐alkynyl‐(hetero)arylcarboxylates. When the alkyne terminus bears a neutral or an electron‐donating group (EDG), the reactions are fast, clean and highly regioselective, to give the 6‐endo‐dig cyclization products in good to excellent yields. For substrates bearing an electron‐withdrawing group (EWG) on the alkyne end, the regioselectivity can be tuned by adding a small amount of silver(I) triflate as co‐catalyst. DES was demonstrated to be reusable without loss of efficiency in terms of reaction yields. Based on experimental evidence and previous findings, two competitive mechanisms working simultaneously are proposed to explain the outcomes and the regioselectivity issues.

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“…), 6.30 (s, 1H, ‐CH‐ sp 2 ), 1.33 [s, 10H, ‐(CH 3 ) 3 ]. Spectral data are in good agreement with literature values …”

Section: Methodssupporting

confidence: 89%

“…of 3p ), 103.3 (‐CH‐ sp 2 of 3p ), 102.9 (‐CH‐ sp 2 of 2p ). The data of compound 2p are in good agreement with literature values . Compound 3p is a new compound.…”

Section: Methodssupporting

confidence: 89%

p‐TSA‐Based DESs as “Active Green Solvents” for Microwave Enhanced Cyclization of 2‐Alkynyl‐(hetero)‐arylcarboxylates: an Alternative Access to 6‐Substituted 3,4‐Fused 2‐Pyranones

et al. 2019

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“…6‐Fluoro‐3‐phenyl‐1 H ‐isochromen‐1‐one (4ba): 14k 4‐Fluoro‐2‐iodobenzoic acid (532 mg, 2.0 mmol) and ethynylbenzne (224 mg, 2.2 mmol) afforded 4ba as a white solid; yield: 326 mg (1.36 mmol, 68%); mp 158–161 °C; 1 H NMR (300 MHz, CDCl 3 ): δ =8.29 (dd, J =8.7, 5.6 Hz, 1 H), 7.86–7.82 (m, 2 H), 7.47–7.40 (m, 3 H), 7.13 (m, 2 H), 6.88 (s, 1 H); 13 C NMR (75 MHz, CDCl 3 ): δ =166.6 (d, J C,F =256.3 Hz), 161.3, 154.8, 140.1(d, J C,F =10.9 Hz), 132.9 (d, J C,F =10.4 Hz), 131.5, 130.3, 128.8, 125.3, 116.9 (d, J C,F =2.0 Hz), 116.4 (d, J C,F =23.3 Hz), 116.5 (d, J C,F =22.6 Hz), 101.1 (d, J C,F =2.9 Hz).…”

Section: Methodsmentioning

confidence: 99%

Modulating the M^II/Pyrimidine‐4,6‐dicarboxylato System by Metal, Solvent and Temperature Variation

Cepeda

Pérez‐Yáñez

2014

Eur J Inorg Chem

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We report herein the synthesis and physicochemical characterisation of seven new compounds employing divalent metal ions and pyrimidine-4,6-dicarboxylato ligand (pmdc):·DMF} n (7) (where phen = 1,10-phenanthroline, form = formamide, DMSO = dimethyl sulfoxide, DMF = dimethylformamide). These compounds are the result of three different approaches that share a common aim: to replace/eliminate coordination solvent molecules to force unusual coordination modes of pmdc that render M II -pmdc polymers with different structural motifs. To this end, we have employed either metal ions that permit high coordination numbers or organic aprotic solvents that can also act as terminal ligands, while different thermal treatments have been applied to both the reaction mixtures as well as solid compounds. The crystal structure of compound 1 contains zig-zag polymeric chains in which mer- [Cd(H 2 2+ units are sequentially joined by means of bis-chelating pmdc ligands. Compound 2 is made up of stacked neutral layers that are built up from the fusion of two independent centrosymmetric [Cd 2 (phen) 2 (μ 3 -pmdc) 2 ] dinuclear units. Hydrothermal

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“…This reaction was then performed under ultrasonication conditions using a combination of CuI‐K 2 CO 3 ‐PEG catalyst to afford a greener route for the synthesis of isocoumarins . An intramolecular CuI‐catalyzed Ullmann‐type C‐arylation followed by rearrangement reaction of 1‐(2‐halophenyl)‐1,3‐diones provided 3‐substituted isocoumarins (Scheme ) …”

Section: Recent Advances In Isocoumarin Synthesismentioning

confidence: 99%

Isocoumarins: General Aspects and Recent Advances in their Synthesis

Saikia

Gogoi

2018

Adv Synth Catal

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Synthesis of 3-Substituted Isocoumarins via a Cascade Intramolecular Ullmann-Type Coupling–Rearrangement Process

Cited by 55 publications

References 58 publications

p‐TSA‐Based DESs as “Active Green Solvents” for Microwave Enhanced Cyclization of 2‐Alkynyl‐(hetero)‐arylcarboxylates: an Alternative Access to 6‐Substituted 3,4‐Fused 2‐Pyranones

p‐TSA‐Based DESs as “Active Green Solvents” for Microwave Enhanced Cyclization of 2‐Alkynyl‐(hetero)‐arylcarboxylates: an Alternative Access to 6‐Substituted 3,4‐Fused 2‐Pyranones

Modulating the M^II/Pyrimidine‐4,6‐dicarboxylato System by Metal, Solvent and Temperature Variation

Isocoumarins: General Aspects and Recent Advances in their Synthesis

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Synthesis of 3-Substituted Isocoumarins via a Cascade Intramolecular Ullmann-Type Coupling–Rearrangement Process

Cited by 55 publications

References 58 publications

p‐TSA‐Based DESs as “Active Green Solvents” for Microwave Enhanced Cyclization of 2‐Alkynyl‐(hetero)‐arylcarboxylates: an Alternative Access to 6‐Substituted 3,4‐Fused 2‐Pyranones

p‐TSA‐Based DESs as “Active Green Solvents” for Microwave Enhanced Cyclization of 2‐Alkynyl‐(hetero)‐arylcarboxylates: an Alternative Access to 6‐Substituted 3,4‐Fused 2‐Pyranones

Modulating the MII/Pyrimidine‐4,6‐dicarboxylato System by Metal, Solvent and Temperature Variation

Isocoumarins: General Aspects and Recent Advances in their Synthesis

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Modulating the M^II/Pyrimidine‐4,6‐dicarboxylato System by Metal, Solvent and Temperature Variation