61676-62-8Relevant articles and documents
A study of the effect on nucleophilic hydrolytic activity of pancreatic elastase, trypsin, chymotrypsin, and leucine aminopeptidase by boronic acids in the presence of arabinogalactan: A subsequent study on the hydrolytic activity of chymotrypsin by boronic acids in the presence of mono-, di-, and trisaccharides
Smoum, Reem,Rubinstein, Abraham,Srebnik, Morris
, p. 464 - 474 (2003)
The hydrolytic activity of trypsin, chymotrypsin, elastase, and leucine aminopeptidase, is inhibited by different boronic acids. However, all the enzymes are inhibited by the compound CbzAla(boro)Gly(OH)2. Therefore, these additives can control the nucleophilic hydrolytic activity of these enzymes.
Hydroboration of nitriles, esters, and amides catalyzed by simple neosilyllithium
Bandyopadhyay, Ayan,Bhattacharjee, Jayeeta,Kumar Singh, Saurabh,Kumari, Kusum,Moorthy, Shruti,Panda, Tarun K.,Sai Kumar, Gobbilla
supporting information, (2022/03/31)
We present here an efficient method for the hydroboration of organic nitriles, carboxylic esters, and carboxamides with pinacolborane (HBpin) using an alkali metal catalyst, neosilyllithium (LiCH2SiMe3), in neat reaction conditions. The reactions were accomplished with efficient catalytic reactivity and demonstrated by neosilyllithium at room temperature, in solvent-free condition, to afford a high yield of the corresponding N-boryl amines, boryl ethers, and amine hydrochlorides. The protocol for the catalytic reaction presented in this paper is simple and efficient, with diverse substrate scope for nitriles, carboxylic esters, and carboxamides showing excellent functional group tolerance. DLPNO-CCSD(T) calculations were also performed, showing that the hydroboration of nitriles catalyzed by neosilyllithium occurs through the pre-coordination of the nitrile at Lewis acid lithium followed by hydride migration from the B–H entity.
Nucleophilic Addition and α-C-H Substitution Reactions of an Imine Mediated by Dibutylmagnesium and Organolithium Reagents
Dang, Yan,Jia, Chaohong,Li, Yafei,Li, Yahong,Lu, Yanhua,Wang, Yalan,Xia, Yuanzhi,Xu, Man,Zhang, Liang
, (2021/07/17)
A series of nucleophilic addition reactions and α-C-H substitution reactions of an imine-containing ligand 2-(2-((((1H-pyrrol-2-yl)methylene)amino)methyl)-1H-pyrrol-1-yl)-N,N-dimethylethan-1-amine (HL1) were reported. The reactions of HL1 with 0.5 and 2 equiv ofnBu2Mg, respectively, gave two complexes of compositions [Mg(L1)2] (1) and [Mg2(L2)2] (2) (H2L2 =N-((1-(2-(dimethylamino)ethyl)-1H-pyrrol-2-yl)methyl)-1-(1H-pyrrol-2-yl)pentan-1-amine). The nucleophilic addition ofnBu2Mg to the C═N bond of the HL1 ligand occurred in the process for the formation of2. Treatment of HL1 with 2 and 1 equiv ofnBuLi generated [Li2(L3)2] (3) (HL3 = 2-(2-(((1-(1H-pyrrol-2-yl)pentylidene)amino)methyl)-1H-pyrrol-1-yl)-N,N-dimethylethan-1-amine) and [Li2(L1)2] (4). An α-C-H substitution of the HC═NR moiety of the HL1 ligand triggered bynBuLi was discovered in the preparation of3. The formation of3demonstrates a new concept for the C-C coupling that involved inert C-H bond activation of HC═NR skeleton. The reactions of HL1 with MeLi,sec-BuLi, and tert-BuLi, respectively, were also examined. The products for both the nucleophilic addition of organolithium reagents to the C═N bond and α-C-H substitution of the HC═NR moiety of the HL1 ligand were determined. The mechanisms for the formations of2and3were rationalized by DFT calculations. The hydroboration reactions catalyzed by2were investigated, and these reactions characterize ample substrate scope, very good yields, and high selectivity.
Metal–Ligand Cooperativity of the Calix[4]pyrrolato Aluminate: Triggerable C?C Bond Formation and Rate Control in Catalysis
Ebner, Fabian,Greb, Lutz,Sigmund, Lukas Maximilian
supporting information, p. 17118 - 17124 (2020/08/21)
Metal-ligand cooperativity (MLC) had a remarkable impact on transition metal chemistry and catalysis. By use of the calix[4]pyrrolato aluminate, [1]?, which features a square-planar AlIII, we transfer this concept into the p-block and fully elucidate its mechanisms by experiment and theory. Complementary to transition metal-based MLC (aromatization upon substrate binding), substrate binding in [1]? occurs by dearomatization of the ligand. The aluminate trapps carbonyls by the formation of C?C and Al?O bonds, but the products maintain full reversibility and outstanding dynamic exchange rates. Remarkably, the C?C bonds can be formed or cleaved by the addition or removal of lithium cations, permitting unprecedented control over the system's constitutional state. Moreover, the metal-ligand cooperative substrate interaction allows to twist the kinetics of catalytic hydroboration reactions in a unique sense. Ultimately, this work describes the evolution of an anti-van't Hoff/Le Bel species from their being as a structural curiosity to their application as a reagent and catalyst.
