Iridium-Catalyzed C-H Borylation of Heteroarenes: Scope, Regioselectivity, Application to Late-Stage Functionalization, and Mechanism was written by Larsen, Matthew A.;Hartwig, John F.. And the article was included in Journal of the American Chemical Society in 2014.SDS of cas: 780705-64-8 This article mentions the following:
A study on the iridium-catalyzed C-H borylation of heteroarenes is reported. Several heteroarenes containing multiple heteroatoms were amenable to C-H borylation catalyzed by the combination of an iridium(I) precursor and tetramethylphenanthroline. The investigations of the scope of the reaction led to the development of powerful rules for predicting the regioselectivity of borylation, foremost of which is that borylation occurs distal to nitrogen atoms. One-pot functionalizations are reported of the heteroaryl boronate esters formed in situ, demonstrating the usefulness of the reported methodol. for the synthesis of complex heteroaryl structures. Application of this methodol. to the synthesis and late-stage functionalization of biol. active compounds is also demonstrated. Mechanistic studies show that basic heteroarenes can bind to the catalyst and alter the resting state from the olefin-bound complex observed during arene borylation to a species containing a bound heteroarene, leading to catalyst deactivation. Studies on the origins of the observed regioselectivity show that borylation occurs distal to N-H bonds due to rapid N-H borylation, creating an unfavorable steric environment for borylation adjacent to these bonds. Computational studies and mechanistic studies show that the lack of observable borylation of C-H bonds adjacent to basic nitrogen is not the result of coordination to a bulky Lewis acid prior to C-H activation, but the combination of a higher-energy pathway for the borylation of these bonds relative to other C-H bonds and the instability of the products formed from borylation adjacent to basic nitrogen. In the experiment, the researchers used many compounds, for example, tert-Butyl 4-(pyrimidin-2-yl)piperazine-1-carboxylate (cas: 780705-64-8SDS of cas: 780705-64-8).
tert-Butyl 4-(pyrimidin-2-yl)piperazine-1-carboxylate (cas: 780705-64-8) belongs to piperazine derivatives. A form in which piperazine is commonly available industrially is as the hexahydrate, C4H10N2. 6H2O, which melts at 44 闁硅櫣鐓?and boils at 125闂?30 闁硅櫣鐓? Piperazine and its salts did not induce point mutations in a bacterial test. A series of mutagenicity studies in cells, both in vitro and in vivo, has been completed and showed no evidence of mutagenic effect.SDS of cas: 780705-64-8
Referemce:
Piperazine – Wikipedia,
Piperazines – an overview | ScienceDirect Topics