59168-51-3Relevant academic research and scientific papers
Enabling Metallophotoredox Catalysis in Parallel Solution-Phase Synthesis Using Disintegrating Reagent Tablets
Borlinghaus, Niginia,Sch?nfeld, Barbara,Heitz, Stephanie,Klee, Johanna,Vukeli?, Stella,Braje, Wilfried M.,Jolit, Anais
, p. 16535 - 16547 (2021/12/02)
Compressed tablets containing a mixture of a photocatalyst, a nickel catalyst, an inorganic base, and an inert excipient are employed as a fast, safe, and user-friendly chemical delivery system for two different metallophotoredox-catalyzed reactions. This delivery method simplifies the preparation of compound libraries using photoredox chemistry in a parallel setting. The reagent tablets were successfully applied to late-stage functionalization of drug-like intermediates. These tablets can be prepared with various reagents and catalysts in different sizes and be stored on the bench thanks to blister packaging.
A Path to More Sustainable Catalysis: The Critical Role of LiBr in Avoiding Catalyst Death and its Impact on Cross-Coupling
Eckert, Philip,Organ, Michael G.
, p. 4861 - 4865 (2020/04/30)
The role that LiBr plays in the lifetime of Pd-NHC complexes has been investigated. A bromide ion is proposed to coordinate to Pd thereby preventing beta hydride elimination (BHE) (to form NHC-H+) of the reductive elimination (RE) intermediate that normally completes with the desired cross-coupling catalytic cycle. Coordinating groups, such as anilines, are able to bind suitably well to Pd to prevent this pathway from occurring, thus reducing the need for the added salt. The metal hydride formed from BHE is very unstable and RE of the hydride to the NHC ligand occurs very rapidly giving rise to the corresponding hydrido-NHC (i.e., NHC-H+). The use of the per deuterated dibutylzinc shows a significant deuterium isotope effect, shutting down catalyst death almost completely. The use of bis-neopentylzinc, now possessing no hydrides, eliminates catalyst death all together leading to a very long-lived catalytic cycle and confirming the untoward role of BHE.
Silyl Radical Activation of Alkyl Halides in Metallaphotoredox Catalysis: A Unique Pathway for Cross-Electrophile Coupling
Zhang, Patricia,Le, Chi Chip,MacMillan, David W. C.
supporting information, p. 8084 - 8087 (2016/07/16)
A strategy for cross-electrophile coupling has been developed via the merger of photoredox and transition metal catalysis. In this report, we demonstrate the use of commercially available tris(trimethylsilyl)silane with metallaphotoredox catalysis to efficiently couple alkyl bromides with aryl or heteroaryl bromides in excellent yields. We hypothesize that a photocatalytically generated silyl radical species can perform halogen-atom abstraction to activate alkyl halides as nucleophilic cross-coupling partners. This protocol allows the use of mild yet robust conditions to construct Csp3-Csp2 bonds generically via a unique cross-coupling pathway.
