The asymmetricepoxidation of chalcone and other electron-poor olefins in a triphasesystem (water-organic solvent-polyaminoacid) affords optically active oxiranes. The influence of the molecular structure of catalysts and of their secondary conformation on the enantioselectivity of the reaction has also been examined.
Investigation of<i>N</i>-carbamoylamino acid nitrosation by {NO + O<sub>2</sub>} in the solid-gas phase. Effects of NO<i>x</i>speciation and kinetic evidence for a multiple-stage process
Nitrosation of N-carbamoylamino acids (CAA) by gaseous NO + O2, an interesting synthetic pathway to amino acid N-carboxyanhydrides (NCA), alternative to the phosgene route, was investigated on N-carbamoyl-valine either in acetonitrile suspension or solventless conditions, and compared to the classical nitrosating system NaNO2 + CF3COOH (TFA), the latter being quite less efficient in terms of either
用气态NO + O 2将N-氨基甲酰基氨基酸(CAA)亚硝化,这是一种有趣的合成方法,可替代光气途径,生成氨基酸N-羧基酸酐(NCA),无论是在乙腈悬浮液中还是在无溶剂的N-氨基甲酰基缬氨酸上与传统的亚硝化系统NaNO 2 + CF 3 COOH(TFA)相比,后者在速率,化学计量需求或产品的进一步可加工性方面都效率较低。NO + O 2反应的速率和效率主要取决于O 2 / NO比。评价各种亚硝化物质(N 2通过化学计量平衡的O 3,N 2 O 4,HNO 2)显示,该反应主要由N 2 O 3(对于低于0.3的O 2 / NO比率)和N 2 O 4(对于高于0.4的O 2 / NO比率)进行。(随后形成的)HNO 2的相对贡献始终保持很小。通过HNO 2(来自NaNO 2 + TFA),气态N 2 O 4或气态N 2 O 3的固相反应的差示扫描量热法(DSC)监控提供了相关的速率常数(分别在25°C时约为0
Revisiting the Juliá–Colonna enantioselective epoxidation: supramolecular catalysis in water
With only water as solvent, poly-l-leucine serves as supramolecular catalyst for the epoxidation of α,β-unsaturated ketones.
只用水作为溶剂,聚-亮氨酸作为α,β-不饱和酮的环氧化反应的超分子催化剂。
The Steric Hindrance of the Stepwise Reaction of<i>N</i>-Carboxy α-Amino Acid Anhydride with the α-Amino Acid Ester
作者:Masanao Oya、Tomoko Takahashi
DOI:10.1246/bcsj.54.2705
日期:1981.9
The mechanisms of the reactions of 4-alkyloxazolidinediones (1) (N-carboxy α-amino acid anhydrides(NCAs)) with α-amino acid benzyl ester p-toluenesulfonates (2) were investigated in acetonitrile containing triethylamine at low and room temperatures. Two types of reactions were observed: (1) the polymerization of NCAs was initiated with a small amount of 2 to produce polypeptides (6), and (2) the dipeptide