A photoreactive crystalline quasiracemate

Grove, Rebecca C.; Malehorn, Steven H.; Breen, Meghan E.; Wheeler, Kraig A.

doi:10.1039/c0cc02775h

Cited by 46 publications

(17 citation statements)

References 35 publications

(4 reference statements)

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“…The cyclobutane rings in these compounds are planar, as it is usually observed for other cyclobutanes containing this arrangement of groups, as are, for instance, the alpha-isomers of the truxillic acid and their related derivatives. 25,[30][31][32] In all cases, the values of the internal parameters for bond distances (Å) and bond angles (°) are as expected, and they do not show unusual deviations from values found in the literature for related structural arrangements. 15,19,25,[28][29][30][31][32][33] Revised manuscript.…”

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confidence: 83%

Metal-Free [2 + 2]-Photocycloaddition of (Z)-4-Aryliden-5(4H)-Oxazolones as Straightforward Synthesis of 1,3-Diaminotruxillic Acid Precursors: Synthetic Scope and Mechanistic Studies

García‐Montero

Rodríguez

Juan

et al. 2017

ACS Sustainable Chem. Eng.

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The direct [2+2]-photocycloaddition of (Z)-2-phenyl-4-aryliden-5(4H)-oxazolones 1 to give 1,3-diaminotruxillic cyclobutane-derivatives 2 in very good yields (75-100%) is reported. The reaction takes place by irradiation of CH2Cl2 solutions of 1 with the blue light (465 nm) provided by LED lamps of low power (around 1 W) for 72 h. Four isomers of the 1,3diaminotruxillic cyclobutanes 2 were obtained, all of them fully characterized by a combination of NMR spectroscopy and X-ray diffraction analysis. The reaction shows a certain selectivity, since one of the isomers (the epsilon) is obtained preferentially, and works for electron-releasing and electron-withdrawing substituents at the arylidene ring. A novel setup is presented for the in-line monitoring of the continuous flow photo-assisted synthesis of the cyclobutane derivatives 2 by NMR spectroscopy, with the microreactor dramatically reducing reaction times to only 30 minutes with clear product distribution of up to four isomers. The mechanism of this [2+2]photocycloaddition has been calculated by DFT methods, explaining all experimental findings. The reaction takes place through a stepwise formation of two new CC bonds through a transient diradical singlet intermediate. The isomeric distribution of the final products is not due to equilibration processes, but instead reflects the kinetic preference during the rate limiting CC bond formation step.

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confidence: 83%

Metal-Free [2 + 2]-Photocycloaddition of (Z)-4-Aryliden-5(4H)-Oxazolones as Straightforward Synthesis of 1,3-Diaminotruxillic Acid Precursors: Synthetic Scope and Mechanistic Studies

García‐Montero

Rodríguez

Juan

et al. 2017

ACS Sustainable Chem. Eng.

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“…6 The design strategy behind these compounds complements current methods that assemble reactive components by promoting reaction atom economy and the construction of chiral crystalline environments for enantioselective transformations. Our crystallographic investigation of racemic and quasiracemic sulfonamidecinnamic acids 1 and 2 revealed structures with isostructural relationships (Scheme 1).…”

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confidence: 99%

Enantiocontrolled solid-state photodimerizations via a chiral sulfonamidecinnamic acid

2011

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“…Upon irradiation, the solid reacted to give the expected cyclobutane product stereo-and regio-specifically in quantitative yield. Similarly, Wheeler and coworkers employed chiral sulfonamidecinnamic acids 60 [96][97][98]. No matter the use of racemic (rac)-60a, quasiracemic [(R)-60a/(S)-60b], and homochiral (R)-60a reagents, the hydrogen bonding dimer persisted and afforded the cyclobutane photoproducts in single-crystal-to-single-crystal (SCSC) transformation (Fig.…”

Section: Self-complementary Reactantsmentioning

confidence: 94%

Hydrogen Bonding in Supramolecular Crystal Engineering

Wang

Zheng

2015

Lecture Notes in Chemistry

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This chapter emphases the important role of hydrogen bonding in crystal engineering for preparing fascinating architectures and engineering desired properties. The relatively high directionality and strength of hydrogen bonds make the prediction and control of molecular orientation in organic solids practical and reliable. Especially, strong hydrogen bonds like O-H···O, O-H···N, and N-H···O interactions are more useful. The introduction of supramolecular synthons and retrosynthesis theory has helped crystal chemists a lot in understanding and designing more complex structures. A large number of crystal structures reported in Cambridge Structure Database (CSD) provided a helpful tool for searching and analyzing specific interaction modes. Up to now, with the development of basic concepts and principles and the wide applications, the subject of crystal engineering has matured. Various intriguing structures and complicated entanglements have been constructed based on hydrogen bonds, such as nanocapsules, nanotubes, and n-Borromean arrayed topologies. The crystal engineering strategy has lent chemists the ability to control solid state reactions regio-and stereo-specifically and improve the physicochemical properties of drugs using pharmaceutical cocrystals. In addition, it will be seen that hydrogen bonding can also be used to prepare robust porous materials for gas adsorption and separation.

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A photoreactive crystalline quasiracemate

Cited by 46 publications

References 35 publications

Metal-Free [2 + 2]-Photocycloaddition of (Z)-4-Aryliden-5(4H)-Oxazolones as Straightforward Synthesis of 1,3-Diaminotruxillic Acid Precursors: Synthetic Scope and Mechanistic Studies

Metal-Free [2 + 2]-Photocycloaddition of (Z)-4-Aryliden-5(4H)-Oxazolones as Straightforward Synthesis of 1,3-Diaminotruxillic Acid Precursors: Synthetic Scope and Mechanistic Studies

Enantiocontrolled solid-state photodimerizations via a chiral sulfonamidecinnamic acid

Hydrogen Bonding in Supramolecular Crystal Engineering

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