Formation of 5,6- and 7,8-dihydrohexahelicene: mechanistic details of the rearrangement of the primary photocyclization product of 2-styrylbenzo[c]phenanthrene in the presence of a base

Prinsen, W. J. C.; Laarhoven, W. H.

doi:10.1021/jo00276a034

Cited by 6 publications

(3 citation statements)

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“…The very first synthesis of [6]helicene was accomplished via a 12-step route in 1956 . Since then, a number of methods for helicene synthesis have been introduced. − Among other approaches, the photochemical method (i.e., oxidative photocyclization) seems to be the most flexible and therefore the most used in helicene chemistry up to now. ,,− The original synthesis established by Mallory is based on the UV-light induced cis/trans photoisomerization of a stilbene derivative followed by a symmetry-allowed conrotatory electrocyclization of the cis isomer to generate the trans -dihydrophenanthrene derivative as an intermediate. In the presence of air and a catalytic amount of iodine, the intermediate is immediately converted by dehydrogenation into a fully aromatic compound.…”

Section: Introductionmentioning

confidence: 99%

Preparation and Physicochemical Properties of [6]Helicenes Fluorinated at Terminal Rings

Cı́rkva¹,

Jakubík²,

Strašák³

et al. 2019

J. Org. Chem.

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The first racemization-stable helicene derivatives fluorinated at terminal rings, 1,2,3,4-tetrafluoro[6]helicene (6) and 1,2,3,4,13,14,15,16-octafluoro[6]helicene (15), were synthesized via the Wittig reaction followed by oxidative photocyclization in an overall yield of 41% of 6 and 76% of 15. The changed electronic structure in fluorinated helicenes was reflected in a slight shift of UV–vis absorption, fluorescence excitation, and emission spectra maxima when compared to unsubstituted [6]helicene. Cyclic voltammetry revealed a moderate decrease in the HOMO–LUMO gap with increasing fluorination. The specific rotation of tetrafluoro[6]helicene 6 enantiomers was found to be approximately 25% lower than that of unsubstituted [6]helicene. The theoretical study of the racemization barrier suggested a reasonable shift toward higher energy with increasing fluorination. The increasing fluorination also significantly affected the intermolecular interactions in the crystal lattice. The observed CH···F interactions led to the formation of 1D-molecular chains in the crystal structures of both fluorinated helicenes.

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Section: Introductionmentioning

confidence: 99%

Preparation and Physicochemical Properties of [6]Helicenes Fluorinated at Terminal Rings

Cı́rkva¹,

Jakubík²,

Strašák³

et al. 2019

J. Org. Chem.

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“…Helicenes are aromatic compounds that perfectly combine π-conjugated structure and helical chirality, and they have been widely utilized in fields including molecular machines, dye materials, asymmetric catalysis, and chiral recognition . Compared with helicenes, hydrohelicenes have not only π-conjugated structure and helical chirality but also flexible skeletons, which can result in their specific photophysical and chiroptical properties . Although these properties could make the hydrohelicenes show wide potential applications in fluorescent sensing, cell fluorescent imaging, organic optical waveguides, full-color emission dyes, and switchable organic dyes, to our knowledge, none of their applications in chiral recognition has been reported so far.…”

Section: Introductionmentioning

confidence: 99%

Synthesis, Structures, and Photophysical Properties of Optically Stable 1,16-Diphenyl-3,14-diaryl-Substituted Tetrahydrobenzo[5]helicenediol Derivatives: Enantioselective Recognition toward Tryptophan Methyl Esters

Fang

Lin

et al. 2017

J. Org. Chem.

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Starting from commercially available 7-methoxytetralone, 1,16-diphenyl-3,14-dibromotetrahydrobenzo[5]helicenediol (Br-H[5]HOL) was conveniently prepared, which underwent efficient resolution to give the optically stable enantiomeric diols in gram scale by HPLC with semipreparative chiral columns. The absolute configurations of the diols were determined by the circular dichroism (CD) spectra and X-ray crystal structure. By Suzuki-Miyaura cross-coupling reactions, a series of enantiopure π-extended 1,16-diphenyl-3,14-diaryltetrahydrobenzo[5]helicenediol derivatives (Ar-H[5]HOL) were further synthesized in high yields. The enantiomeric Ar-H[5]HOL exhibited almost identical absorption and emission spectra but showed mirror-image CD spectra and mirror-image circularly polarized luminescence properties. Moreover, it was also found that aryl substituents at the 3,14-positions could extend the chiral environment of the helical skeletons, which led to efficient enantioselective recognition of the enantiomers of tryptophan methyl esters.

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“…This probably represents the most useful and versatile synthesis of phenanthrenes . This reaction is equally useful for the preparation of the heterocyclic analogues of phenanthrenes, the so-called “phenanthrenoids”, which are similarly prepared from “stilbenoids.”…”

Section: Introductionmentioning

confidence: 99%

Preparation of Phenanthrenes by Photocyclization of Stilbenes Containing a Tosyl Group on the Central Double Bond. A Versatile Approach to the Synthesis of Phenanthrenes and Phenanthrenoids

et al. 2010

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We have developed a useful modification of the classical preparation of phenanthrenes by UV irradiation of stilbenes in the presence of an oxidant. This modification involves the irradiation, in the presence of base, of stilbenes possessing a sulfonyl group linked to the central double bond. We have proved that this protocol can be successfully applied for the synthesis of diverse phenanthrenes and phenanthrenoids.

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Formation of 5,6- and 7,8-dihydrohexahelicene: mechanistic details of the rearrangement of the primary photocyclization product of 2-styrylbenzo[c]phenanthrene in the presence of a base

Cited by 6 publications

References 0 publications

Preparation and Physicochemical Properties of [6]Helicenes Fluorinated at Terminal Rings

Preparation and Physicochemical Properties of [6]Helicenes Fluorinated at Terminal Rings

Synthesis, Structures, and Photophysical Properties of Optically Stable 1,16-Diphenyl-3,14-diaryl-Substituted Tetrahydrobenzo[5]helicenediol Derivatives: Enantioselective Recognition toward Tryptophan Methyl Esters

Preparation of Phenanthrenes by Photocyclization of Stilbenes Containing a Tosyl Group on the Central Double Bond. A Versatile Approach to the Synthesis of Phenanthrenes and Phenanthrenoids

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