engleski

Photoheterolysis reactions of meta-substituted aminonaphthalene photocages

Photocages are protecting groups that undergo release of a target molecule in a photochemical reaction, activating its function. To date, a scant number of models have been provided that relate the reactivity and structure of photocages undergoing excited-state heterolytic bond cleavage, in contrast to the ground-state reactivity. [1] Winter suggested a hypothesis for the structure-reactivity relationship for the excited state heterolysis, which takes place under conical intersection control. Unstabilized cations favored from photochemical heterolysis were found to have low-energy conical intersections, while stabilized cations from thermal heterolysis have high-energy unfavorable conical intersections. [1] Based on the meta-effect in photochemistry, [2] a series of aniline derivatives were investigated as photocages for carboxylic acids and alcohols. [3] Furthermore, to enable excitation by photons of lower energy, we developed a series of differently substituted aminonaphthalene derivatives as potential photocages for alcohols and carboxylic acids. [4] We found out that ortho-derivatives show excellent performance in decaging carboxylic acids ; the photorelease from 2, 3-substituted photocages takes place more efficiently (acetate elimination, Φ=0.11), than from 1, 2-substituted photocages (acetate elimination, Φ=0.01). [4] However, these ortho-derivatives did not show good performance as photocages for alcohols. In accordance with the meta-effect, [2] it was expected that the meta-derivatives would show even better photodeprotection efficiency compared to the ortho- derivatives. Herein we present synthesis and photochemistry of 3, 1-substituted aminonaphthalene photocages. We have shown excellent performance of the ester derivative in the decaging of carboxylic acids (acetate elimination, Φ=0.22). Furthermore, ethers also undergo photoelimination of alcohols, albeit less efficiently (Figure 1).

Aminonaphthalenes ; Photocages ; Photochemistry

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