Photochemical syntheses, transformations, and bioorthogonal chemistry of<i>trans</i>-cycloheptene and sila<i>trans</i>-cycloheptene Ag(<scp>i</scp>) complexes

Fang, Yinzhi; Zhang, Han; Huang, Zhen; Scinto, Samuel L.; Yang, Jeffrey; Ende, Christopher W. am; Dmitrenko, Olga; Johnson, Douglas S.; Fox, Joseph M.

doi:10.1039/c7sc04773h

Cited by 42 publications

(36 citation statements)

References 78 publications

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“…Fox and co-workers synthesised trans-cycloheptene photochemically from cis-cycloheptene (82) using a closed loop photochemical flow reactor via metal complexation of the trans-isomer (Scheme 28). [73,94] This involved the trans-isomer being selectively retained by the silver nitrate (83), while the cis-isomer 82 runs off with silica within the flow reactor. The proclivity of trans-cycloalkenes to form stable Ag(I) salts -whereas cis-isomers generally do notis a general property of this class of compounds and appears to be due to a strain release of the severely twisted trans C=C bond.…”

Section: Trans-cycloheptenementioning

confidence: 99%

Highly Strained Unsaturated Carbocycles

et al. 2020

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Highly strained unsaturated carbocyclic rings are high‐energy compounds which are attracting increasing interest – not just for their peculiar structural and reactivity features – but also as modern chemical tools for bioorthogonal and in vivo chemistry, especially via inverse‐electron demand Diels–Alder (iEDDA) and strain‐promoted azide‐alkyne cycloaddition (SPAAC) reactions. This mini‐review covers two main classes of compounds: 3 to 10 membered‐ring cycloalkynes and trans‐cycloalkenes, including some examples of cyclic enynes, dienes and bridgehead alkenes. Their molecular properties, synthesis and reactivity are presented and discussed, with an emphasis on their functionalization and reactivity.

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Section: Trans-cycloheptenementioning

confidence: 99%

Highly Strained Unsaturated Carbocycles

et al. 2020

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“…However, flow photochemistry can be used to prepare trans-cycloheptenes and sila-trans-cycloheptenes as their isolable Ag-complexes. [152] Photoisomerizations to form sila-trans-cycloheptene silver nitrate (Si-TCH · AgNO 3 ) complexes were carried out at r.t. using the standard flow-photoisomerization apparatus (254 nm), with the modification that Si-TCH · AgNO 3 complexes were directly isolated from SiO 2 without Ag-decomplexation. The Si-TCH · AgNO 3 complexes are stable in neat form for > 1 month in the freezer.…”

Section: Flow Photochemical Synthesis Of Trans-cycloheptenes and Silamentioning

confidence: 99%

“…Vicinal dihydroxylation with OsO 4 and NMO gave the trans-diol in 82 % yield as a single diastereomer. [152] Si-TCH complex 15 was obtained treating the silver complex with NH 4 OH and directly subjected to reactions cyclopentadiene, diazomethane, dichloroketene, and benzyl azide to give cycloadducts as single diastereomers in 76 %-96 % yields (Figure 18). With cycloadduct 16, it was shown that the diphenylsila-group could be oxidized to diol product 17 in 76 % yield.…”

Section: Flow Photochemical Synthesis Of Trans-cycloheptenes and Silamentioning

confidence: 99%

“…With cycloadduct 16, it was shown that the diphenylsila-group could be oxidized to diol product 17 in 76 % yield. [152] In bioorthogonal reactions, Si-TCH compounds are 1.4-2.8x more reactive than s-TCO depending upon the context of tetrazine reaction partner and reaction conditions. As shown in Figure 19, the reaction of a fluorescent dipyridyltetrazine conjugate with a Si-TCH in 9 : 1 water:MeOH at 25°C proceeds with a second order rate constant k 2 1.14 × 10 7 (+ /À 5 × 10 5 ) M À 1 s À 1 .…”

Section: Flow Photochemical Synthesis Of Trans-cycloheptenes and Silamentioning

confidence: 99%

“…The cell labeling experiments show that Si-TCH derivatives are suitably stable to serve as highly reactive probe molecules in the cellular environment. [152]…”

Section: Flow Photochemical Synthesis Of Trans-cycloheptenes and Silamentioning

confidence: 99%

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Flow Photochemical Syntheses of trans‐Cyclooctenes and trans‐Cycloheptenes Driven by Metal Complexation

Pigga

Fox

2019

Israel Journal of Chemistry

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trans-Cyclooctenes and trans-cycloheptenes have long been the subject of physical organic study, but the broader application had been limited by synthetic accessibility. This account describes the development of a general, flow photochemical method for the preparative synthesis of trans-cycloalkene derivatives. Here, photoisomerization takes place in a closed-loop flow reactor where the reaction mixture is continuously cycled through Ag(I) on silicagel. Selective complexation of the trans-isomer by Ag(I) during flow drives an otherwise unfavorable isomeric ratio toward the transisomer. Analogous photoreactions under batch-conditions are low yielding, and flow chemistry is necessary in order to obtain trans-cycloalkenes in preparatively useful yields. The applications of the method to bioorthogonal chemistry and stereospecific transannulation chemistry are described.The unusual reactivity and well-defined chiral structure of trans-cycloalkenes has made them attractive targets for synthesis for nearly 70 years. [1][2][3] For example, trans-cyclooctene possesses planar chirality and displays a high barrier to racemization (E a = 35.6 kcal/mol), [4] and the most stable "crown" conformer has an alternating sequence of equatorial and axial hydrogens that is akin to chair cyclohexane. [5][6] The double bond of trans-cyclooctene is twisted severely in the crown conformation, [7] and as a consequence the HOMO of trans-cyclooctene is relatively high in energy. [8] trans-Cycloheptene also has a rigid structure with a distorted alkene. [7] The double bonds of medium-ring trans-alkenes are twisted. [7] trans-Cycloalkenes display unusual reactivity in HOMOalkene controlled cycloaddition reactions with dienes, [9] 1,3dipoles [8] and ketenes. [10] Strained trans-cycloalkenes also serve as ligands for transition metals. [11][12][13][14][15][16] This reactivity profile has made trans-cycloalkanes interesting targets for applications in synthesis and biology.The broadest applications of trans-cycloalkenes are in the field of bioorthogonal chemistry. The inverse-electron demand Diels-Alder reaction between tetrazines and strained alkenes has a rich history in physical organic and synthetic chemistry (Figure 1). [17][18][19] In 2008, three groups described the bioorthogonal reactions of tetrazines with strained alkenes. [20][21][22] The variant introduced by our group that used trans-cyclooctene is marked by exceptionally rapid kinetics, with rate constants that can exceed 10 6 M À 1 s À 1 in the fastest cases. [23][24] With the advances including the development of fluorogenic tetrazines [25] and reactions in live cells [26] and animals, [27] the tetrazine ligation has become a widely used tool for applications that span chemical biology, biomedical imaging, and materials science. [28][29][30][31][32][33][34][35][36][37] This account describes the development of general, flow photochemical methods for the preparative synthesis of transcycloalkene derivatives and enabled applications in synthesis and bioorthogonal chemistry. Selectiv...

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Metabolic Glycan Engineering in Live Animals: Using Bio‐orthogonal Chemistry to Alter Cell Surface Glycans

Dube

Williams

2019

Handbook of in Vivo Chemistry in Mice

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Photochemical syntheses, transformations, and bioorthogonal chemistry oftrans-cycloheptene and silatrans-cycloheptene Ag(i) complexes

Abstract: Synthesis and transformations of AgNO3 complexes of trans-cycloheptene (TCH) and trans-1-sila-4-cycloheptene (Si-TCH) derivatives are described.

Cited by 42 publications

References 78 publications

Highly Strained Unsaturated Carbocycles

Highly Strained Unsaturated Carbocycles

Flow Photochemical Syntheses of trans‐Cyclooctenes and trans‐Cycloheptenes Driven by Metal Complexation

Metabolic Glycan Engineering in Live Animals: Using Bio‐orthogonal Chemistry to Alter Cell Surface Glycans

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