Cascade reactions in crystals through cation–π-controlled reorientation on exposure to HCl gas

Yamada, Shinji; Tokugawa, Yoko; Nojiri, Yuka; Takamori, Eri

doi:10.1039/c2cc17019a

Cited by 26 publications

(12 citation statements)

References 34 publications

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“…Recent studies established 16 stilbazoles and 4-azachalcone, 1-aryl-4-pyridylbutadiene photodimerized to a single anti head-tail dimer in the solid state in the presence of HCl–H 2 O (Scheme ). − The importance of water in this process became evident when dry HCl instead of aqueous HCl was used to protonate the stilbazoles. Examination of the packing arrangements of two stilbazolium salts shown in Figure revealed that hydrogen bonding between N–H---O and N–H---Cl – controlled the packing.…”

Section: Organic Crystals As a Supramolecular Assemblymentioning

confidence: 99%

Supramolecular Photochemistry as a Potential Synthetic Tool: Photocycloaddition

2016

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Photochemistry, bearing significant applications in natural and man-made events such as photosynthesis, vision, photolithography, photodynamic therapy, etc., is yet to become a common tool during the synthesis of small molecules in a laboratory. Among other rationale, the inability to influence photochemical reactions with temperature, solvent, additives, etc., dissuades chemists from employing light-initiated reactions as a routine synthetic tool. This review highlights how diverse, highly organized structures such as solvent-free crystals and water-soluble host-guest assemblies can be employed to control and manipulate photoreactions and thereby serve as an efficient tool for chemists, including those interested in synthesis. The efficacy of the media in modifying the excited-state behavior of organic molecules is illustrated with photocycloaddition in general and [2 + 2] photocycloaddition in particular, reactions widely employed in the synthesis of complex natural products as well as highly constrained molecules, as exemplars. The reaction media, highly pertinent in the context of green sustainable chemistry, include solvent-free crystals and solids such as silica, clay, and zeolite and water-soluble hosts that can solubilize and preorganize hydrophobic reactants in water. Since no other reagent would be more sustainable than light and no other medium greener than water, we believe that the supramolecular photochemistry expounded here has a momentous role as a synthetic tool in the future.

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Section: Organic Crystals As a Supramolecular Assemblymentioning

confidence: 99%

Supramolecular Photochemistry as a Potential Synthetic Tool: Photocycloaddition

2016

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“…Irradiation of the obtained HCl salt afforded the synHT dimers in high regio-and stereoselectivities (Scheme 126). 344 Figure 22 shows photomicrographs of a single crystal of 486 before and after exposure to HCl gas. After exposure for 10 min, unevenness and cracking were observed and the initial transparency was almost lost.…”

Section: Photodimerization In Solutionmentioning

confidence: 99%

Cation−π Interactions in Organic Synthesis

2018

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The cation−π interaction is an attractive noncovalent interaction between a cation and a π system. Due to the stronger interaction energy than those of the other π interactions, such as π–π and CH−π interactions, the cation−π interaction has recently been recognized as a new tool for controlling the regio- and stereoselectivities in various types of organic reactions. This review attempts to cover a variety of organic reactions controlled by cation−π interactions, which includes not only recent examples but also those reported before the term “cation−π interaction” was defined in 1990. This review will provide comprehensive knowledge on the role of cation−π interactions in organic synthesis.

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“…Leider können die exakten supramolekularen Verhältnisse nicht aus den aktuellen Daten abgeleitet werden. Erstaunlicherweise wurde eine Änderung der Kristallstruktur durch den Einfluss von gasförmiger HCl auch bei verschiedenen anderen organischen Strukturen beobachtet, beispielsweise durch Amin‐Protonierung, wobei diese Änderung ausschließlich bei gasförmiger HCl auftreten …”

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