A new procedure for the reductive desulfonylation of β-keto sulfones is described. The reaction proceeds under a photochemical conditions with the Hantzschester in pyridine in the presence of ruthenium(II). Various functional groups are unaffected under the reaction conditions. Application of the procedure to the syntheses of certain natural products is also described.
描述了一种用于 β-酮砜还原脱磺酰化的新程序。在钌 (II) 存在下,该反应在光化学条件下与在吡啶中的 Hantzsch 酯进行。各种官能团在反应条件下不受影响。还描述了该程序在某些天然产物合成中的应用。
A Titanium‐Catalyzed Reductive α‐Desulfonylation
作者:Christoph Kern、Jan Selau、Jan Streuff
DOI:10.1002/chem.202005400
日期:2021.4.7
building blocks from α‐sulfonyl nitriles, circumventing traditional base‐mediated α‐alkylation conditions and strong single electron donors. The reaction tolerates numerous functional groups including free alcohols, esters, amides, and it can be applied also to the α‐desulfonylation of ketones. In addition, a one‐pot desulfonylative alkylation is demonstrated. Preliminary mechanistic studies indicate a catalyst‐dependent
Reaction of β-keto phenylsulphone tosylhydrazones 2 with 2 eq. of DBU, at r.t. in dichloromethane, affords α,β-unsaturated ketone tosylhydrazones 4, via the tosylazoalkenes 3 obtained by 1,4-elimination of benzenesulfinic acid.
Red Light-Based Dual Photoredox Strategy Resembling the Z-Scheme of Natural Photosynthesis
作者:Felix Glaser、Oliver S. Wenger
DOI:10.1021/jacsau.2c00265
日期:2022.6.27
typically relies on the use of single chromophores, whereas strategies, in which two different light absorbers are combined, are rare. In photosystems I and II of green plants, the two separate chromophores P680 and P700 both absorb light independently of one another, and then their excitation energy is combined in the so-called Z-scheme, to drive an overall reaction that is thermodynamically very demanding
光氧化还原催化通常依赖于使用单个发色团,而将两种不同的光吸收剂组合在一起的策略很少见。在绿色植物的光系统 I 和 II 中,两个独立的发色团 P 680和 P 700都相互独立地吸收光,然后它们的激发能量在所谓的 Z 方案中组合,以驱动热力学上的整体反应非常严格。在这里,我们采用这个概念在有机基材上进行光氧化还原反应,其中两个红色光子的组合能量输入而不是蓝色或紫外光。具体来说,Cu I双(α-二亚胺)配合物与原位结合在过量的二异丙基乙胺催化下形成 9,10-二氰基蒽自由基阴离子。50 次脱卤和脱甲苯基反应。这种双重光氧化还原方法似乎很有用,因为红光的破坏性较小,并且比蓝光或紫外线辐射具有更大的穿透深度。紫外-可见瞬态吸收光谱表明,溶剂从乙腈到丙酮的细微变化会引起反应机制的转变,包括主要的光诱导电子转移或主要的三重态-三重态能量转移途径。我们的研究说明了在多光子激发条件下运行的系统的机械复杂