Department of Chemistry, Iowa State University, 1608 Gilman Hall, Ames, Iowa50010, United States.
J Org Chem. 2022 Nov 4;87(21):14334-14341. doi: 10.1021/acs.joc.2c01781. Epub 2022 Oct 18.
BODIPY-based photocages release substrates by excitation with wavelengths in the visible to near-IR regions. The recent development of more efficient BODIPY photocages spurred us to evaluate the scope and efficiency of these second-generation boron-methylated green-light and red-light-absorbing BODIPY photocages. Here, we show that these more photosensitive photocages release amine, alcohol, phenol, phosphate, halides, and carboxylic acid derivatives with much higher quantum yields than first-generation BODIPY photocages and excellent chemical yields. Chemical yields are near-quantitative for the release of all functional groups except the photorelease of amines, which react with concomitantly photogenerated singlet oxygen. In these cases, high chemical yields for photoreleased amines are restored by irradiation under an inert atmosphere. The photorelease quantum yield has a weak relationship with the leaving group p of the green-absorbing BODIPY photocages but little relationship with the red-absorbing derivatives, suggesting that factors other than leaving group quality impact the quantum yield. For the photorelease of alcohols, in all cases a carbonate linker (that loses CO upon photorelease) significantly increases both the quantum yield and the chemical yield compared to those for direct photorelease via the ether.
基于 BODIPY 的光解笼通过在可见到近红外区域的波长激发来释放底物。最近更高效的 BODIPY 光解笼的发展促使我们评估这些第二代硼甲基化绿光和红光吸收 BODIPY 光解笼的范围和效率。在这里，我们表明，这些对光更敏感的光解笼以比第一代 BODIPY 光解笼更高的量子产率释放胺、醇、酚、磷酸盐、卤化物和羧酸衍生物，并且具有出色的化学产率。除了与同时光生成的单线态氧反应的胺的光释放之外，所有官能团的释放都接近定量的化学产率。在这些情况下，通过在惰性气氛下照射可以恢复对光释放的胺的高化学产率。光释放量子产率与绿光吸收 BODIPY 光解笼的离去基团 p 呈弱相关，但与红光吸收衍生物几乎没有关系，这表明除了离去基团质量之外的其他因素会影响量子产率。对于醇的光释放，在所有情况下，与直接通过醚进行光释放相比，碳酸酯连接基团（在光释放时失去 CO）显著提高了量子产率和化学产率。
