Photolysis of diarylvinylcyclopropenes for the construction of 1-methylene-8a-aryl-1,8a-dihydroazulene skeletons

Yu, Fangfang; Yang, Wanggui; Shi, Min

doi:10.1039/b820212e

Cited by 12 publications

(5 citation statements)

References 29 publications

(2 reference statements)

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“…The conjugated part of DHA has seven possible positions (C2, C3, C4, C5, C6, C7, and C8; for numbering, see Scheme ) at which its properties can be potentially tuned by substituent groups and at which it can be incorporated into larger systems. We have very recently taken the first step toward advancing the chemistry of the seven-membered ring. , Thus, an efficient regioselective bromination-elimination protocol was devised for preparing the bromo-substituted DHA 2a from DHA 1a (Chart ). Special care was required in the elimination step to avoid elimination of HCN along with HBr, which would furnish the corresponding 10π-aromatic azulene.…”

Section: Introductionmentioning

confidence: 99%

Arylethynyl Derivatives of the Dihydroazulene/Vinylheptafulvene Photo/Thermoswitch: Tuning the Switching Event

et al. 2010

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A selection of dihydroazulene (DHA) photoswitches incorporating an arylethynyl-substituent in the seven-membered ring was prepared by palladium-catalyzed Sonogashira cross-coupling reactions employing a suitable bromo-functionalized DHA. Shielding of the alkyne bridge and separating the aryl and DHA units, by sterically demanding groups, was required to obtain stable compounds. The DHAs underwent a light-induced ring-opening to vinylheptafulvenes (VHFs) which were thermally converted to a mixture of two DHA regioisomers, one of which was the original one. The influence of the aryl groups on the DHA and VHF absorptions and on their interconversion was investigated in detail. The rates of the switching events were finely tuned by the donor or acceptor strength of the aryl group. The thermal ring closure was found to proceed most readily in the presence of an electron-donating group on the seven-membered ring. The rate constant was found to follow a Hammett linear free energy correlation, which signals that stabilization of a positive charge in the seven-membered ring plays a crucial role in the ring-closure reaction. In view of these findings, it was possible to control the switching event by protonation/deprotonation of an anilino-substituted DHA. Also, the light-induced ring opening reaction was strongly controlled by acid/base. In addition to the mesomeric effects exerted by an arylethynyl group, the inductive effects exerted by different groups on the thermal ring closure were elucidated. Although the alkyne bridge transmits the electronic character of the aryl group, the ring-closure is retarded for all the ethynylated compounds relative to the parent unsubstituted compound. Along with our synthesis of suitable arylalkynes, we discovered an interesting byproduct in a Sonogashira cross-coupling reaction involving a nitrophenyl group, namely a diaryl azoxy compound. Its structure was confirmed by X-ray crystallographic analysis.

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Section: Introductionmentioning

confidence: 99%

Arylethynyl Derivatives of the Dihydroazulene/Vinylheptafulvene Photo/Thermoswitch: Tuning the Switching Event

et al. 2010

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“…In 2009, Shi and co-workers studied the photochemical behavior of 2-vinylcyclopropenes 193 (Scheme 54A). 255 Thus, irradiation with UV light using Pyrex tubes led to the formation of azulene derivatives 365 in good yields. Importantly, this reaction outcome contrasts with those observed in Brønsted acid-or metal-catalyzed reactions which resulted in the formation of indene derivatives.…”

Section: Rearrangements Of Cyclopropenes Via C−c Bond Cleavagementioning

confidence: 99%

“…In 2009, Shi and co-workers studied the photochemical behavior of 2-vinylcyclopropenes 193 (Scheme A) . Thus, irradiation with UV light using Pyrex tubes led to the formation of azulene derivatives 365 in good yields.…”

Section: Photochemical Ring-opening Reactions Of Cyclopropenesmentioning

confidence: 99%

C–C Bond Cleavages of Cyclopropenes: Operating for Selective Ring-Opening Reactions

Vicente

2020

Chem. Rev.

117

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This review highlights key reactivities relying on C–C bond cleavages of cyclopropenes. Metal-catalyzed and metal-free transformations are covered in reactions involving direct ring-opening processes or transformations through nonisolable cyclopropane intermediates generated from cyclopropenes. Special emphasis is on the synthetic utility and mechanistic aspects of methodologies discussed along the revision. Different types of reactivities are covered in separate sections including generation of vinyl carbenes and their reactions, metathesis processes, heterocycles syntheses, SEAr reactions, metalation-ring opening sequences, cycloadditions involving ring-cleavages or rearrangements. The focus is on results described from 2007 to the end of 2019, yet relevant pioneering transformations are eventually included.

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“…Intramolecular carbene insertion of 260 followed by ringopening of tricyclic-compound 261 provides final product 259 (Scheme 55). 175…”

Section: Photoisomerizationmentioning

confidence: 99%

Recent developments of cyclopropene chemistry

2011

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This critical review discusses recent developments in the field of cyclopropene chemistry. Although several excellent reviews that mainly focused on the thermolysis and pyrolysis as well as metal-mediated reactions of cyclopropenes have been published, significant new developments have also been achieved in recent years. This brand new review provides an overview of the progress from 2007 to 2011 on the syntheses and transformations of cyclopropenes as well as their related mechanistic studies (238 references).

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Photolysis of diarylvinylcyclopropenes for the construction of 1-methylene-8a-aryl-1,8a-dihydroazulene skeletons

Abstract: Photoirradiation of vinylcyclopropenes in a Pyrex tube provides 1-isopropylidene-3,8a-diphenyl-1,8a-dihydroazulene derivatives in moderate to good yields within 4.5-14 h. A plausible mechanism has been discussed for the formation of these interesting products.

Cited by 12 publications

References 29 publications

Arylethynyl Derivatives of the Dihydroazulene/Vinylheptafulvene Photo/Thermoswitch: Tuning the Switching Event

Arylethynyl Derivatives of the Dihydroazulene/Vinylheptafulvene Photo/Thermoswitch: Tuning the Switching Event

C–C Bond Cleavages of Cyclopropenes: Operating for Selective Ring-Opening Reactions

Recent developments of cyclopropene chemistry

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