Models for the use of .alpha.-amino acids as chiral auxiliaries in asymmetric Diels-Alder reactions
摘要:
Three different models, depending on the Lewis acid used as a catalyst and the alpha-amino acid used as a chiral auxiliary, account for the diastereofacial selectivity obtained in reactions of cyclopentadiene with N-acryloyl derivatives of L-proline, L-phenylalanine, L-alanine, and N-methyl-L-alanine esters. For alpha-amino acids without an NH group and aluminum catalysts, a reactive conformer with antiplanar enoate conformation similar to those postulated for acrylates with only one center capable of coordination is proposed. These dienophiles form a chelate complex, where the acryloyl moiety is in syn conformation, with TiCl4. For alpha-amino acids with an NH group, a reactive intermediate with an antiplanar disposition in the acryloyl moiety and the conformation of the amino ester fixed by an intramolecular hydrogen bond accounts for the results with both kinds of catalyst. These models seem to have general application for the use of alpha-amino acids as chiral auxiliaries in asymmetric Diels-Alder reactions.
Photoredox/Cobalt Dual Catalysis for Visible-Light-Mediated Alkene–Alkyne Coupling
作者:Pramod Rai、Kakoli Maji、Biplab Maji
DOI:10.1021/acs.orglett.9b01201
日期:2019.5.17
Dual photoredox transition-metal catalysis has recently emerged as a powerful tool for making synthetically challenging carbon–carbon bonds under milder reaction conditions. Herein, we report on the visible-light-mediated controlled generation of low-valent cobalt catalyst without the need for a metallic reductant. It enabled C–C bondformation via ene-yne coupling at roomtemperature. The generality
Controlling Amphiphilic Polymer Folding beyond the Primary Structure with Protein-Mimetic Di(Phenylalanine)
作者:Jacqueline L. Warren、Peter A. Dykeman-Bermingham、Abigail S. Knight
DOI:10.1021/jacs.1c05659
日期:2021.8.25
functionality pales in comparison to natural biopolymers–strategies are limited for building the intricate network of noncovalent interactions necessary to elicit complex, protein-like functions. Using a bioinspired di(phenylalanine) acrylamide (FF) monomer, we explored the impact of various noncovalent interactions in generating ordered assembled structures. Amphiphiliccopolymers were synthesized that
METALLOPROTEASE INHIBITORS, METHODS FOR PRODUCING SAME, AND THERAPEUTIC USES THEREOF
申请人:CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE - CNRS
公开号:US20160200676A1
公开(公告)日:2016-07-14
The invention relates to new α-vinyl carbonylated compounds corresponding to general formula (I), wherein R
1
, R
2
, R
3
, R
4
, R
5
and Y are as defined in claim
1
, their isomers, their diastereoisomers and acid addition salts or a pharmaceutically acceptable base. The invention also relates to a method for producing said compounds (I). It further relates to the use of said compounds (I) as selective metalloprotease inhibitors, especially matrix metalloproteases 12 (MMP-12) and/or 9 (MMP-9). The compounds (I) are particularly useful for the prevention and/or treatment of chronic obstructive pulmonary disease (COPD), particularly emphysema induced by cigarette smoke.
functionalized acyclic chiral pyrroloamide compounds were synthesized by a simple and robust process involving the creation of a C-C bond between unprotected pyrroles and acyclic chiral acrylamides using Lewis acids. This alkylation reaction using Michael acceptors has been optimized, allowing us to obtain channel selective access to monoalkylated or dialkylated pyrroles, in good yields. Di- and tripeptide deriving
Poly(<i>N</i>-acryl amino acids): A New Class of Biologically Active Polyanions
作者:Alfonso Bentolila、Israel Vlodavsky、Rivka Ishai-Michaeli、Olga Kovalchuk、Christine Haloun、Abraham J. Domb
DOI:10.1021/jm000089j
日期:2000.6.1
derivatives of the active polymers, zwitterionic amino acid dependent groups (lysine, histidine), and decarboxylated amino acids (tyramine, ethanolamine) were inactive. The above active polymers did not exhibit anticoagulation activity which is considered the main limitation of heparin and heparinomimetics for clinical use. These synthetic poly(N-acryl amino acids) may have potential use in the inhibition
由N-丙烯酸的自由基聚合合成带有侧基的亲脂性或带电荷的官能团(即-NH(2),-COOH,-SH,-OH和酚)的聚(N-丙烯酸氨基酸)氨基酸单体。单体是由丙烯酰氯与氨基酸酯在干燥溶剂中反应制得的。获得了3000至60000Da的宽分子量的聚合物。该聚合物是光学活性的,并且它们的结构通过(1)1 H NMR和IR光谱以及元素分析得到证实。含羟基的聚合物被SO(3)/吡啶配合物高转化率硫酸化。测试了新合成的线性均聚阴离子的肝素样活性:(i)抑制乙酰肝素酶,(ii)从细胞外基质(ECM)释放碱性成纤维细胞生长因子(bFGF),(iii)抑制平滑肌细胞(SMC)增殖。基于酪氨酸和亮氨酸的聚合物在所有三个测试中均具有很高的活性(微克水平)。基于苯丙氨酸,叔亮氨酸和脯氨酸的聚合物具有乙酰肝素酶抑制剂和FGF释放的活性,而反式羟脯氨酸,甘氨酸和丝氨酸的聚合物仅具有乙酰肝素酶抑制剂的活性。顺式羟脯氨酸的聚