A general strategy for visible-light decaging based on the quinone cis-alkenyl lock

Selective deprotection of functional groups using different wavelengths of light is attractive for materials synthesis as well as for achieving independent photocontrol over substrates in biological systems. However, wavelength-selective activation is difficult to achieve with common UV-absorbing photoremovable protecting groups (PRPGs) because it is difficult to separate the chromophore absorption profiles. Moreover, deep UV irradiation of photocages can result in cellular phototoxicity. Here, we investigated the ability of recently-developed visible light absorbing BODIPY-derived PRPGs and a coumarin-derived PRPG to undergo wavelength selective activation in order to identify well-behaved pairs of PRPGs that allow independent optical control over a mixture of photocaged substrates using more biologically benign long-wavelength light. The three pairs of PRPGs tested have complete selectivities for cleaving the longerwavelength absorbing photocage first, and fair to excellent selectivities for releasing the lower-wavelength absorbing PRPG first when mixtures were irradiated in solution. When the PRPGs are attached to the same substrate, irradiating the shorter-wavelength absorbing PRPG results in energy transfer, but the PRPGs can be cleaved in a sequential manner starting by deprotecting the longest wavelength absorbing photocage first and then removing the lower-wavelength absorbing PRPG. A mixture of the three photocages could be sequentially reacted using common red, green, and far-UV (365 nm) LED irradiation.

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Multiwavelength Control of Mixtures Using Visible Light Absorbing Photocages

10.26434/chemrxiv.13010075 ◽

2020 ◽

Author(s):

Julie A Peterson ◽

Ding Yuan ◽

Arthur Winter

Keyword(s):

Visible Light ◽

Optical Control ◽

Protecting Groups ◽

Materials Synthesis ◽

Selective Activation ◽

Long Wavelength ◽

Photoremovable Protecting Groups ◽

Deep Uv ◽

Wavelength Light ◽

Led Irradiation

Selective deprotection of functional groups using different wavelengths of light is attractive for materials synthesis as well as for achieving independent photocontrol over substrates in biological systems. However, wavelength-selective activation is difficult to achieve with common UV-absorbing photoremovable protecting groups (PRPGs) because it is difficult to separate the chromophore absorption profiles. Moreover, deep UV irradiation of photocages can result in cellular phototoxicity. Here, we investigated the ability of recently-developed visible light absorbing BODIPY-derived PRPGs and a coumarin-derived PRPG to undergo wavelength selective activation in order to identify well-behaved pairs of PRPGs that allow independent optical control over a mixture of photocaged substrates using more biologically benign long-wavelength light. The three pairs of PRPGs tested have complete selectivities for cleaving the longerwavelength absorbing photocage first, and fair to excellent selectivities for releasing the lower-wavelength absorbing PRPG first when mixtures were irradiated in solution. When the PRPGs are attached to the same substrate, irradiating the shorter-wavelength absorbing PRPG results in energy transfer, but the PRPGs can be cleaved in a sequential manner starting by deprotecting the longest wavelength absorbing photocage first and then removing the lower-wavelength absorbing PRPG. A mixture of the three photocages could be sequentially reacted using common red, green, and far-UV (365 nm) LED irradiation.

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8-[4-(2-Hydroxypropane-2-yl)Phenyl]-1,3,4,4,5,7-Hexamethyl-4-Boron-3a,4a-Diaza-S-Indacene

Molbank ◽

10.3390/m1286 ◽

2021 ◽

Vol 2021 (4) ◽

pp. M1286

Author(s):

Anastasiya Zobnina ◽

Alexander Moskalensky ◽

Aleksey Vorob’ev

Keyword(s):

Visible Light ◽

13C Nmr ◽

Protecting Groups ◽

Photoremovable Protecting Groups

During recent years, the BODIPY core became a popular scaffold for designing photoremovable protecting groups (PPG). In this paper, we report the synthesis of a new molecule—8-[4-(2-hydroxypropane-2-yl)phenyl]-1,3,4,4,5,7-hexamethyl-4-boron-3a,4a-diaza-S-indacene—by the treatment of meso-(4-CO2Me-phenyl)-BODIPY with excess of MeMgI. The product was characterized by 1H, 13C NMR and HRMS. The combination of BODIPY core with tertiary benzilyc alcohol might be promising for utilizing this molecule as visible light removable PPG.

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Visible Light-Mediated Oxidative Debenzylation

10.26434/chemrxiv.13135814 ◽

2020 ◽

Author(s):

Cristian Cavedon ◽

Eric T. Sletten ◽

Amiera Madani ◽

Olaf Niemeyer ◽

Peter H. Seeberger ◽

...

Keyword(s):

Reaction Time ◽

Visible Light ◽

Functional Groups ◽

Continuous Flow ◽

Protecting Groups ◽

Benzyl Ether ◽

Complex Molecules ◽

Protective Groups ◽

Benzyl Ethers ◽

Harsh Conditions

Protecting groups are key in the synthesis of complex molecules such as carbohydrates to distinguish functional groups of similar reactivity. The harsh conditions required to cleave stable benzyl ether protective groups are not compatible with many other protective and functional groups. The mild, visible light-mediated debenzylation disclosed here renders benzyl ethers orthogonal protective groups. Key to success is the use of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) as stoichiometric or catalytic photooxidant such that benzyl ethers can be cleaved in the presence of azides, alkenes, and alkynes. The reaction time for this transformation can be reduced from hours to minutes in continuous flow.

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Visible-Light Photosensitized Aryl and Alkyl Decarboxylative Carbon-Heteroatom and Carbon-Carbon Bond Formations

10.26434/chemrxiv.7995983.v1 ◽

2019 ◽

Author(s):

Tuhin Patra ◽

Satobhisha Mukherjee ◽

Jiajia Ma ◽

Felix Strieth-Kalthoff ◽

Frank Glorius

Keyword(s):

Energy Transfer ◽

Visible Light ◽

Alkyl Radical ◽

General Strategy ◽

Alkyl Radicals ◽

Bond Forming ◽

Radical Trapping ◽

Carbon Carbon Bond ◽

Radical Generation ◽

Trapping Agent

A general strategy to access both aryl and alkyl radicals by photosensitized decarboxylation of the corresponding carboxylic acids esters has been developed. An energy transfer mediated homolysis of unsymmetrical sigma-bonds for a concerted fragmentation/decarboxylation process is involved. As a result, an independent aryl/alkyl radical generation step enables a series of key C-X and C-C bond forming reactions by simply changing the radical trapping agent.

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Photoreleasable Protecting Groups Triggered by Sequential Two-Photon Absorption of Visible Light: Release of Carboxylic Acids from a Linked Anthraquinone-N-Alkylpicolinium Ester Molecule

The Journal of Physical Chemistry A ◽

10.1021/acs.jpca.8b00657 ◽

2018 ◽

Vol 122 (12) ◽

pp. 3204-3210 ◽

Cited By ~ 4

Author(s):

Matthew D. Thum ◽

Daniel E. Falvey

Keyword(s):

Visible Light ◽

Carboxylic Acids ◽

Photon Absorption ◽

Protecting Groups ◽

Two Photon Absorption ◽

Two Photon ◽

Ester Molecule

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Competing pathways for photoremovable protecting groups: the effects of solvent, oxygen and encapsulation

Photochemical & Photobiological Sciences ◽

10.1039/d0pp00067a ◽

2020 ◽

Vol 19 (10) ◽

pp. 1364-1372

Author(s):

Thomas Field ◽

Julie Peterson ◽

Chicheng Ma ◽

Pradeepkumar Jagadesan ◽

José P. Da Silva ◽

...

Keyword(s):

Reaction Mechanism ◽

Protecting Groups ◽

Photoremovable Protecting Groups ◽

Competing Pathways

Photolysis of p-hydroxyphenacyloxy arenes releases free phenols in good yields governed by their pKa. At high pKa, new byproducts (Bvs. A) reveal a change in reaction mechanism.

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