2252-50-8Relevant articles and documents
Reactivity control of a photocatalytic system by changing the light intensity
Kerzig, Christoph,Wenger, Oliver S.
, p. 11023 - 11029 (2019/12/28)
We report a novel light-intensity dependent reactivity approach allowing us to selectively switch between triplet energy transfer and electron transfer reactions, or to regulate the redox potential available for challenging reductions. Simply by adjusting the light power density with an inexpensive lens while keeping all other parameters constant, we achieved control over one- and two-photon mechanisms, and successfully exploited our approach for lab-scale photoreactions using three substrate classes with excellent selectivities and good product yields. Specifically, our proof-of-concept study demonstrates that the irradiation intensity can be used to control (i) the available photoredox reactivity for reductive dehalogenations to selectively target either bromo- or chloro-substituted arenes, (ii) the photochemical cis-trans isomerization of olefins versus their photoreduction, and (iii) the competition between hydrogen atom abstraction and radical dimerization processes.
Fluorine as an ortho-directing group in aromatic metalation: Generality of the reaction and the high position of fluorine in the Dir-Met potency scale
Bridges,Lee,Maduakor,Schwartz
, p. 7495 - 7498 (2007/10/02)
Many para-substituted fluorobenzenes can be lithiated ortho to fluorine in moderate to good yields, often with one of the dialkylamide bases, lithium diisopropylamide (LDA) or lithium 2,2,6,6-tetramethylpiperidide (LiTMP). Intramolecular competition experiments reveal that fluorine is one of the most potent Dir-Met activating groups under these conditions.
