170942-79-7Relevant articles and documents
Flexible Coordination of N,P-Donor Ligands in Aluminum Dimethyl and Dihydride Complexes
Falconer, Rosalyn L.,Nichol, Gary S.,Cowley, Michael J.
, p. 11439 - 11448 (2019)
Aluminum hydrides, once a simple class of stoichiometric reductants, are now emerging as powerful catalysts for organic transformations such as the hydroboration or hydrogenation of unsaturated bonds. The coordination chemistry of aluminum hydrides supported by P donors is relatively underexplored. Here, we report aluminum dihydride and dimethyl complexes supported by amidophosphine ligands and study their coordination behavior in solution and in the solid state. All complexes exist as κ2-N,P complexes in the solid state. However, we find that for amidophosphine ligands bearing bulky aminophosphine donors, aluminum dihydride and dimethyl complexes undergo a "ligand-slip" rearrangement in solution to generate κ2-N,N complexes. Thus, importantly for catalytic activity, we find that the coordination behavior of the P donor can be modulated by controlling its steric bulk. We show that the reported aluminum hydrides catalyze the hydroboration of alkynes by HBPin and that the variable coordination mode exhibited by the amidophosphine ligand modulates the catalytic activity.
Origins of Internal Regioselectivity in Copper-Catalyzed Borylation of Terminal Alkynes
Tsushima, Takumi,Tanaka, Hideya,Nakanishi, Kazuki,Nakamoto, Masaaki,Yoshida, Hiroto
, p. 14381 - 14387 (2021/12/01)
Installation of a boron functionality into a more substituted carbon of terminal alkynes has been a challenging issue in chemical synthesis, since inherently Lewis acidic boron moieties, in principle, favor their attachment to a terminal carbon. Herein, we report on the highly internal-selective borylation of terminal alkynes under copper catalysis, wherein diminishment of boron-Lewis acidity and ligand-derived steric bulk around a copper center are the key to the success. In particular, the use of an anthranilamide-substituted boron moiety [B(aam)] is of high synthetic significance, because its properly diminished Lewis acidity enabled the internal regioselectivity and the Suzuki-Miyaura cross-coupling activity to be compatibly achieved. This method provided a direct and universal approach to variously substituted branched alkenylboron compounds, regardless of electronic and steric properties of a substituent on terminal alkynes.
H2-Acceptorless Dehydrogenative Boration and Transfer Boration of Alkenes Enabled by Zirconium Catalyst
Shi, Xiaonan,Li, Sida,Wu, Lipeng
supporting information, p. 16167 - 16171 (2019/11/03)
The first example of an efficient and direct dehydrogenative boration of alkenes for vinyl boronate ester synthesis was achieved using a zirconium catalyst. Our methodology avoids using precious transition metals, additional hydrogen acceptors, high temperatures, and long reaction times, which were required to overcome the reducing ability of borane, to give alkyl boronate esters. Detailed mechanistic studies revealed a reversible reaction pathway and further suggested applying the zirconium complex as a “shuttle catalyst” for transfer boration, which thus sidesteps the use of relatively sensitive borane.
