Sunscreen-Assisted Selective Photochemical Transformations

• Published in: Molecules (Basel, Switzerland) Vol. 25; no. 9; p. 2125
• Main Authors: Eivgi, Or, Lemcoff, N Gabriel
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 01.05.2020; MDPI
• Subjects: Absorptivity; Catalysis; Chemical interactions; chromatic selectivity; Chromophores; Electromagnetic absorption; Light; Metathesis; Molecular Structure; Natural products; Photochemical Processes; Photochemical reactions; Photochemicals; photochemistry; photoinduced olefin metathesis; photolabile protecting groups; Photosensitivity; Protecting group removal; Review; Sunscreen; Sunscreening Agents - chemistry; Wavelengths; photolabile protecting groups; sunscreen; photoinduced olefin metathesis; chromatic selectivity; photochemistry
• ISSN: 1420-3049; 1420-3049
• DOI: 10.3390/molecules25092125

In this review, we describe a simple and general procedure to accomplish selective photochemical reaction sequences for two chromophores that are responsive to similar light frequencies. The essence of the method is based on the exploitation of differences in the molar absorptivity at certain wavelengths of the photosensitive groups, which is enhanced by utilizing light-absorbing auxiliary filter molecules, or "sunscreens". Thus, the filter molecule hinders the reaction pathway of the least absorbing molecule or group, allowing for the selective reaction of the other. The method was applied to various photochemical reactions, from photolabile protecting group removal to catalytic photoinduced olefin metathesis in different wavelengths and using different sunscreen molecules. Additionally, the sunscreens were shown to be effective also when applied externally to the reaction mixture, avoiding any potential chemical interactions between sunscreen and substrates and circumventing the need to remove the light-filtering molecules from the reaction mixture, adding to the simplicity and generality of the method.