Methods of synthesis of cyclobutenediones

Amere, Mukkanti; Periasamy, Muthu

doi:10.3998/ark.5550190.0006.b07

Cited by 5 publications

(5 citation statements)

References 7 publications

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“…More recently, a [2+2] cycloaddition of di-tertbutoxyacetylene has been used to generate squaric acid. 2,3 At present, squaric acid and related squarate building blocks such as squaric esters, squarate dichlorides and squaramides are commercially available from a variety of suppliers. Owing to this ready availability, publications on the synthesis and applications of squarate derivatives are increasingly appearing in the literature.…”

Section: Synthetic Chemistry Of Squarate Derivatives 31 Preparation O...mentioning

confidence: 99%

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Squaramides: physical properties, synthesis and applications

2011

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Squaramides are remarkable four-membered ring systems derived from squaric acid that are able to form up to four hydrogen bonds. A high affinity for hydrogen bonding is driven through a concomitant increase in aromaticity of the ring. This hydrogen bonding and aromatic switching, in combination with structural rigidity, have been exploited in many of the applications of squaramides. Substituted squaramides can be accessed via modular synthesis under relatively mild or aqueous conditions, making them ideal units for bioconjugation and supramolecular chemistry. In this tutorial review the fundamental electronic and structural properties of squaramides are explored to rationalise the geometry, conformation, reactivity and biological activity.

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Section: Synthetic Chemistry Of Squarate Derivatives 31 Preparation O...mentioning

confidence: 99%

“…For additional reference, several reviews and book chapters have been written that provide more comprehensive details of aspects of the synthesis of squarate systems. 2,3…”

Section: Introductionmentioning

confidence: 99%

Squaramides: physical properties, synthesis and applications

2011

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“…To date, there are several reports in the literature describing the introduction of simple alkyl, aryl, heteroaryl, alkynyl, and alkenyl 11 functional groups in those positions of cyclobutenedione. However, they require the use of highly reactive Grignard or organolithium derivatives which limits the functional groups that can withstand these reaction conditions.…”

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confidence: 99%

Pd-Catalyzed, Cu(I)-Mediated Cross-Couplings of Bisarylthiocyclobutenediones with Boronic Acids and Organostannanes

2007

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Bisarylthiocyclobutenedione 7 reacted smoothly with a variety of both organostannanes and (hetero) aryl boronic acids in the presence of a catalytic amount of Pd and a stoichiometric amount of CuTC, to produce symmetrical disubstituted cyclobutenediones in yields that range from 37 to 94% (18 examples).Over the last three decades, various research groups have demonstrated the remarkable versatility of cyclobutenedione 1 and squaric acid ester derivatives 2 in the synthesis of organic compounds. Particularly, the groups of Liebeskind, 1 Moore, 2 Paquette, 3 and Danheiser 4 have been very active in this area.Starting from either 1 or 2, a wide variety of different compounds have been prepared, including triquinanes 3, 3a angularly-fused aromatic systems 4 ,5 bisquaryls 5 ,6 and 2-pyrones 6 7 just to mention a few (Figure 1).Squaric acid derivatives have also been used as ion sensors, 8 ligands, 9 and to prepare cyclo [n]carbons. 10 E-mail: eduardop@quijote.ugto.mx. † Universidad de Guanajuato ‡ Emory University Supporting Information Available: Experimental procedures and compound characterization data, copies of the NMR spectra of the compounds prepared. This material is available free of charge via the Internet at http://pubs.acs.org. Accordingly, the need for new protocols that allow for a practical functionalization of the 3 and 4 positions becomes evident. NIH Public AccessTo date, there are several reports in the literature describing the introduction of simple alkyl, aryl, heteroaryl, alkynyl, and alkenyl 11 functional groups in those positions of cyclobutenedione. However, they require the use of highly-reactive Grignard or organolithium derivatives which limits the functional groups that can withstand these reaction conditions. Few milder transition metal-mediated methods to prepare such derivatives have been reported. Namely, Knochel et al. reported the reaction of 3,4-dichlorocyclobutendione and zinc-copper reagents. 12 Likewise, Liebeskind disclosed an efficient synthesis of 3-(tri-n-butylstannyl)-3-cyclobutene-1,2-dione. This stannylcyclobutenedione underwent cross-couplings with organic iodides and triflates catalyzed by the PhCH 2 ClPd(PPh 3 ) 2 /CuI system. 1k,6,13 The same group reported the Stille couplings of monohalocyclobutenediones with organostannanes. 14 Against this background, we decided to explore the use of the palladium-catalyzed, coppermediated cross-couplings of thioorganics with both organostannanes and boronic acids 15 to develop a mild protocol to functionalize the vinyl positions of cyclobutenedione with both aryl and heteroaryl groups.Bisthiocyclobutenediones 7-9 where prepared in order to study the influence of the substituent on sulfur in the cross-couplings. Thus, the corresponding thiols were reacted with 3,4-dichlorocyclobutene-1,2-dione 16 10 in the presence of triethylamine (Scheme 1).Thiocyclobutenediones 7-9 were obtained in a straightforward manner as stable yellow powders which could be handled in air with no evident signs of decomposition even after several w...

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“…A summary of the general considerations for the synthesis of symmetric and non-symmetric squaraine dyes is presented below. For more detailed, substrate-specific synthetic approaches, some recent reviews could be consulted [9][10][11].…”

Section: Synthesis Of Squaraine Dyes: General Considerationsmentioning

confidence: 99%

Squaraine-Based Optical Sensors: Designer Toolbox for Exploring Ionic and Molecular Recognitions

Dzyuba

2021

Chemosensors

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Small molecule-based chromogenic and fluorogenic probes play an indispensable role in many sensing applications. Ideal optical chemosensors should provide selectivity and sensitivity towards a variety of analytes. Synthetic accessibility and attractive photophysical properties have made squaraine dyes an enticing platform for the development of chemosensors. This review highlights the versatility of modular assemblies of squaraine-based chemosensors and chemodosimeters that take advantage of the availability of various structurally and functionally diverse recognition motifs, as well as utilizing additional recognition capabilities due to the unique structural features of the squaraine ring.

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Methods of synthesis of cyclobutenediones

Cited by 5 publications

References 7 publications

Squaramides: physical properties, synthesis and applications

Squaramides: physical properties, synthesis and applications

Pd-Catalyzed, Cu(I)-Mediated Cross-Couplings of Bisarylthiocyclobutenediones with Boronic Acids and Organostannanes

Squaraine-Based Optical Sensors: Designer Toolbox for Exploring Ionic and Molecular Recognitions

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