In this work, the [2+2] photocycloaddition of carbonylcompounds with olefins, the Paterno-Buchi-type photoreaction, was performed in a flow microreactor under slug flow (two-phase flow) conditions...
Rapid Regio- and Diastereoselective Paternò−Büchi Reaction of Alkyl Phenylglyoxylates
作者:Shengkui Hu、Douglas C. Neckers
DOI:10.1021/jo9615054
日期:1997.2.1
excited states of alkyl phenylglyoxylates react rapidly (k = 9.4 x 10(9) M(-)(1) s(-)(1)) with electron rich alkenes forming oxetanes with high regio and stereoselectivity. The well-known intramolecular gamma-hydrogen abstraction (NorrishtypeII) cannot compete. When less electron-rich alkenes are used, the NorrishtypeIIreaction becomes competitive. Intramolecular Paternò-Büchi reactions predominate
烷基苯乙醛酸酯的三重激发态快速反应(k = 9.4 x 10(9)M(-)(1)s(-)(1))与富含电子的烯烃形成氧杂环丁烷,具有较高的区域和立体选择性。众所周知的分子内γ-氢提取(Norrish II型)无法竞争。当使用较少的富电子烯烃时,Norrish II型反应变得具有竞争性。分子内的Paternò-Büchi反应在含有适当定位的富电子烯基的烷基苯基乙醛酸酯中占主导地位。该反应的区域选择性由中间体1,4-双自由基的稳定性来解释。系统间交叉时的适当构象决定了产物的立体选择性。
Remarkable Improvement of Organic Photoreaction Efficiency in the Flow Microreactor by the Slug Flow Condition Using Water
A typical (Paternò-Büchi type) organicphotoreaction is examined in flow microreactors. Compared to the results achieved for simple one-layer flow modes, slug flow conditions (with the unreactive reagent composed of organic solution and water) achieve higher efficiency (conversion and yield) irrespective of the light source, concentration, and solvent. Furthermore, remarkably high productivity is also
Divergent Photocatalytic Reactions of α-Ketoesters under Triplet Sensitization and Photoredox Conditions
作者:Jian Zheng、Xiao Dong、Tehshik P. Yoon
DOI:10.1021/acs.orglett.0c02314
日期:2020.8.21
The long-lived triplet excited states of transition metal photocatalysts can activate organic substrates via either energy- or electron-transfer pathways, and the rates of these processes can be influenced by rational tuning of the reaction conditions. The characteristic reactive intermediates generated, however, are distinct and can exhibit very different reactivity patterns. This mechanistic diversity