Highly Enantioselective Intra- and Intermolecular [2 + 2] Photocycloaddition Reactions of 2-Quinolones Mediated by a Chiral Lactam Host: Host−Guest Interactions, Product Configuration, and the Origin of the Stereoselectivity in Solution
The [2 + 2] photocycloaddition of 4-alkoxy-2-quinolones was conducted in the presence of the chiral lactams 5 or ent-5. At -60 degrees C in toluene as the solvent the intramolecular reaction of quinolones 6 and 8 as well as the intermolecularphotocycloaddition of various alkenes 13 to quinolone 12 proceeded with excellent enantioselectivity (81-98% ee) and in high yields (61-89%). Styrene (13d) reacted
A designed photoenzyme for enantioselective [2+2] cycloadditions
作者:Jonathan S. Trimble、Rebecca Crawshaw、Florence J. Hardy、Colin W. Levy、Murray J. B. Brown、Douglas E. Fuerst、Derren J. Heyes、Richard Obexer、Anthony P. Green
DOI:10.1038/s41586-022-05335-3
日期:2022.11.24
accessible to biocatalysis.5-12 Installation of a genetically encoded photosensitiser into the beta-propeller scaffold of DA_20_0013 converts a de novo Diels-Alderase into a photoenzyme for [2+2]-cycloadditions (EnT1.0). Subsequent development and implementation of a platform for photoenzyme evolution afforded an efficient and enantioselective enzyme (EnT1.3, up to 99% e.e.) that can promote intramolecular
将新的催化模式编程到蛋白质中的能力将允许开发具有超出自然界中发现的功能的酶家族。为此,遗传密码扩展方法具有特别的前景,因为它允许将新的功能元件作为非规范氨基酸侧链选择性地引入蛋白质中。 1-4在这里,我们利用扩展的遗传密码来开发一种通过三重态能量转移催化发挥作用的光酶,这是有机合成中的一种多功能反应模式,目前生物催化无法实现。 5-12将基因编码的光敏剂安装到 DA_20_00 13的 β 螺旋桨支架中,将de novo Diels-Alderase 转化为用于 [2+2]-环加成的光酶 (EnT1.0)。随后光酶进化平台的开发和实施提供了一种高效的对映选择性酶(EnT1.3,高达 99% ee ),可以促进分子内和双分子环加成,包括已证明用小分子催化剂选择性实现具有挑战性的转化。 EnT1.3 的转换次数超过 300 次,与小分子光催化剂相比,它可以在有氧条件和环境温度下有效运行。 EnT1
Kaneko, Chikara; Suzuki, Takeshi; Sato, Masayuki, Chemical and pharmaceutical bulletin, 1987, vol. 35, # 1, p. 112 - 123
KANEKO CH.; SUZUKI TAKESHI; SATO MASAYUKI; NAITO TOSHIHIKO, CHEM. AND PHARM. BULL., 35,(1987) N 1, 112-123
作者:KANEKO CH.、 SUZUKI TAKESHI、 SATO MASAYUKI、 NAITO TOSHIHIKO
DOI:——
日期:——
High Triplet Energy Iridium(III) Isocyanoborato Complex for Photochemical Upconversion, Photoredox and Energy Transfer Catalysis
作者:Lucius Schmid、Felix Glaser、Raoul Schaer、Oliver S. Wenger
DOI:10.1021/jacs.1c11667
日期:2022.1.19
reactions, and they are of interest for upconversion into the ultraviolet spectral range. However, the triplet energies of commonly employed Ir(III) photosensitizers are typically limited to values around 2.5–2.75 eV. Here, we report on a new Ir(III) luminophore, with an unusually high triplet energy near 3.0 eV owing to the modification of a previously reported Ir(III) complex with isocyanoborato ligands
环金属化 Ir(III) 配合物通常被选为具有挑战性的光氧化还原和三重态-三重态能量转移 (TTET) 催化反应的催化剂,并且它们对于上转换到紫外光谱范围内具有重要意义。然而,常用的 Ir(III) 光敏剂的三重态能量通常限制在 2.5-2.75 eV 左右。在这里,我们报告了一种新的 Ir(III) 发光体,由于先前报道的 Ir(III) 配合物与异氰硼酸配体的修饰,其三重态能量异常高,接近 3.0 eV。与非硼化氰基前体配合物相比,引入 B(C 6 F 5 ) 3除了高三重态能量外,第二配位球中的单元可显着改善光物理性质,特别是高发光量子产率(0.87)和长激发态寿命(13.0 μs)。这些有利的特性(包括良好的长期光稳定性)促进了极具挑战性的有机三重态光反应和(敏化)三重态-三重态湮没上转换为超过 4 eV 的荧光单重态激发态,在紫外区域非常深。新的 Ir(III) 配合物光催化 sigmatropic