seven chiral azolinium and five functionalized chiral azolinium salts, precursors to N-heterocyclic carbenes, derived from l-proline has been developed. Moderate to good overall yields were obtained. Some NHC dimers and thiones were isolated. X-ray crystal structure determinations of two [Rh-NHC] complexes were also reported. A short and flexible procedure for the preparation of seven chiral azolinium
l-proline amide moiety and a terminal hydroxyl for catalyzing direct asymmetric aldol reactions of aldehydes in neat acetone are designed and prepared. Catalyst 3d, prepared from l-proline and (1S,2S)-diphenyl-2-aminoethanol, exhibits high enantioselectivities of up to 93% ee for aromaticaldehydes and up to >99% ee for aliphatic aldehydes. A theoretical study of transition structures demonstrates the important
设计并制备了含有 l-脯氨酸酰胺部分和末端羟基的新型有机分子,用于催化醛在纯丙酮中的直接不对称羟醛反应。由 l-脯氨酸和 (1S,2S)-二苯基-2-氨基乙醇制备的催化剂 3d 对芳香醛的对映选择性高达 93% ee,对脂肪醛的对映选择性高达 >99%。过渡结构的理论研究证明了催化剂中末端羟基在立体识别中的重要作用。我们的研究结果表明,在设计用于直接不对称醛醇反应和相关转化的新型有机催化剂方面采用了一种新策略,因为在设计中可能会采用大量含有多氢键供体(例如肽)的手性资源。
Tri- and tetrapeptide analogs of kinins as potential renal vasodilators
作者:Francis R. Pfeiffer、Pamela A. Chambers、Eileen E. Hilbert、Paul W. Woodward、Dennis M. Ackerman
DOI:10.1021/jm00369a017
日期:1984.3
Tri- and tetrapeptide analogues were synthesized and evaluated as renal vasodilators. These peptides were prepared by standard coupling reactions, which also provided good yields with hindered alpha-methyl amino acid derivatives. Preliminary evidence of renal vasodilator activity was determined in anesthetized dogs by measuring the effects on renal blood flow and calculating the accompanying changes in renal vascular resistance. The most potent compounds contained, in their basic structure, the L-prolyl-DL-alpha-methylphenylalanyl-L-arginine and L-prolyl-DL-alpha-methylphenylalanylglycyl-L-proline arrays. Substitution on the N-terminal proline with 4-phenylbutyryl and 4-(4-hydroxyphenyl)butyryl side chains produced enhanced renal vasodilator activity and, in certain cases, selectivity for the renal vasculature.
Inhibition of α-chymotrypsin with thiol-bearing substrate analogues in the presence of zinc ion
作者:Min Su Han、Dong Ju Oh、Dong H. Kim
DOI:10.1016/j.bmcl.2003.11.058
日期:2004.2
We have demonstrated that thiol-bearing analogues of alpha-chymotrysin (alpha-CT) substrates such as (S)-(1-benzyl-2-thiolethyl)-carbamic acid, benzyl ester (3) inhibits (alpha-CT, a prototypical serine protease, in the presence of Zn(II) ion. They constitute a novel class of small molecule inhibitors for alpha-CT believed to inhibit the enzyme by forming a ternary complex consisting of alpha-CT, Zn(II) ion, and the inhibitor. (C) 2003 Elsevier Ltd. All rights reserved.