2818-70-4Relevant academic research and scientific papers
Exploring the Strength of the H-Bond in Synthetic Models for Heme Proteins: The Importance of the N?H Acidity of the Distal Base
Alberti, Mariza N.,Polyhach, Yevhen,Tzirakis, Manolis D.,T?dtli, Laura,Jeschke, Gunnar,Diederich, Fran?ois
supporting information, p. 10194 - 10202 (2016/07/19)
The distal hydrogen bond (H-bond) in dioxygen-binding proteins is crucial for the discrimination of O2with respect to CO or NO. We report the preparation and characterization of a series of ZnIIporphyrins, with one of three meso-phenyl rings bearing both an alkyl-tethered proximal imidazole ligand and a heterocyclic distal H-bond donor connected by a rigid acetylene spacer. Previously, we had validated the corresponding CoIIcomplexes as synthetic model systems for dioxygen-binding heme proteins and demonstrated the structural requirements for proper distal H-bonding to CoII-bound dioxygen. Here, we systematically vary the H-bond donor ability of the distal heterocycles, as predicted based on pKavalues. The H-bond in the dioxygen adducts of the CoIIporphyrins was directly measured by Q-band Davies-ENDOR spectroscopy. It was shown that the strength of the hyperfine coupling between the dioxygen radical and the distal H-atom increases with enhanced acidity of the H-bond donor.
Indium-mediated one-pot benzimidazole synthesis from 2-nitroanilines or 1,2-dinitroarenes with orthoesters
Kim, Jaeho,Kim, Jihye,Lee, Hyunseung,Lee, Byung Min,Kim, Byeong Hyo
experimental part, p. 8027 - 8033 (2011/11/06)
One-pot reduction-triggered heterocyclizations from 2-nitroanilines or 1,2-dinitroarenes to benzimidazoles were investigated in this study. In the presence of indium/AcOH in ethyl acetate at reflux, reaction of 2-nitroanilines or 1,2-dinitroarenes with R-C(OMe)3 (R=Me, Ph) produced excellent yields of the corresponding benzimidazoles within 30 min to 6 h depending on the substituents of the starting materials. Indium-mediated heterocyclization of 2-nitroanilines to benzimidazole was faster and had better yields than 1,2-dinitroarenes to benzimidazole under similar reaction conditions.
