We report an organocatalyst that combines a triazolium N-heterocyclic carbene (NHC) with a squaramide as a hydrogen-bonding donor (HBD), which can effectively catalyze the atroposelective ring-opening of biaryl lactams via a unique amide C–N bond cleavage mode. The free carbene species attacks...
FTIR results show that the H-bond is formed by NH...carbonyl (C=O) (Type I) in PUMHS while the H-bond is mainly formed by NH...ether(O) (Type II) in PUMSS; the amide II band, however, is more related to the Type II H-bonding interaction while amide III band is more 展开...
Inversion transfer (13)C NMR spectroscopy and IR spectroscopy were used to compare the ability of various amide solvents and of water to alter the rate of the cis-trans isomerization of the prolyl peptide bond of Ac-Gly-[β,δ-(13)C]Pro-OMe and the amide I vibrational mode of [(13)C...
The structural sensitivity of the corresponding amide I mode, which is predominantly a CO stretching vibration, is generally attributed to the influence of hydrogen bonding on the force constant of the carbonyl bond.Reinhard Schweitzer-Stenner
The connectivity of the glucose moiety was determined by observing the correlation between the anomeric proton signal (d 5.05) and the corresponding carbon signal C-11 (d 156.4) in the HMBC experiment to form a glycoside bond (Figure 4c). Thus, the structure of 7 was elucidated as shown in...
The amide bond is an important linkage ubiquitous in nature and technology found in many small molecules and materials. Formation of amide bonds is most easily accomplished via condensation at high temperatures using amines and carboxylic acids, but peptide coupling agents are pervasively used to form...
To finalize the structure of 2, five amide bonds between Val′ and LA, Ile and avCys, Ala5 and Ile, Leu and Ala5 and hdmHis and Leu were identified by three-bond couplings from α-methine protons to amide carbonyl carbons. A 1H–13C long-range coupling from an olefin proton (δH ...
3) amide bridge bond 酰胺桥键4) aromatic amide bonds 芳酰胺键 1. Two kinds of liquid crystalline bismaleimides (Ⅰb and Ⅱb) containing aromatic amide bonds in their backbone were synthesized. 通过对马来酰亚胺基苯甲酸及其酰氯化路线合成了两种含芳酰胺键的液晶双马来酰亚胺Ⅰ b和Ⅱ b;制备...
In the present experiments, the sizes range from 1.7 to 9.8 nm. Such variation makes it possible to determine the influence of the size of the water pool on water H-bond structure and dynamics and the distribution of NMA-d7 solute in the RM. The approximate sizes of the water pools as...
Distortion of the amide bond in amides and lactams. Photoelectron-spectrum and electronic structure of 3,5,7-trimethyl-1-azaadamantan-2-one, the most twist... We report the He(I) photoelectron spectrum of 3,5,7-trimethyl-1-azaadamantan-2-one (20). Ionization potentials have been assigned...