Studies On Supramolecular Chemistry Of Peptides, Zn-Proline Catalyzed Henry Reaction And Chemoseletive Esterification Of Phenolic Acids

Part 1. In the past three decades, many progress has been made in supramolecular chemistry, which focuses on the weak interactions between molecules. Molecular recognition and molecular self-assembly through the non-covalent bond is the two important parts of supramolecular chemistry. According to the intermolecular non-covalent bond is the core synthetic method to form all kinds of supramolecular system. On the other hand, molecular recognition is very significant to asynmmetric synthesis and enantiomers' separation.In recent years there has been intense interest in the design of pseudo-peptide oligomers that fold into well- defined secondary structures. Such structural mimics are not only important for a rational design of simple, low molecular weight pharmaceutical agents, but also provide information on complex structure-activity relationships and valuable insight into the forces that control protein folding.Since the 2,6-bis(carbamoyl)pyridine group was found to be a good template for constructing simple mimics of protein secondary structures, and for metal binding, at the same time it was a special example in determining the molecular self-assembly through providing the n-n interactions, incorporation of other privileged structural elements could be expected to further increase its utility. In this paper, We wish to disclose our recent findings on the novel aggregation behavior of the 2,6-bis(carbamoyl)pyridine-modified peptides 4, 5 and 6, which can self-assemble into H-bonded infinite P-sheet-like ribbon ,water channel and extended a helix bundles in the solid state respectively. X-ray diffraction analysis reveals that the 6-Cu(II) complex resulting in the formation of two types of macrocyclic cavities, one is filled with water molecules and the other with methanol molecules. NMR study showed that peptide 6 is an efficient receptor for halide ions at the same time. We also synthesized 2,6-bis(carbonyl)pyridine-modified peptides 8a-c which can coordinate withCu2+ and Ni2+, and the further studies is in progress.Part 2. The Henry or nitroaldol reaction, which essentially is a coupling reaction between a carbonyl compound and a nitroalkane having a-hydrogen atoms, constitutes a fundamental synthetic tool for the construction of C-C bonds in organic chemistry. The importance of the Henry reaction is typically further transformations involving the newly formed /?-nitroalkanol functionality such as reduction, oxidation, or dehydration, depending on the requirements and overall goal of the multi-step synthetic plan.Classical methods for preparing /?-nitroalkanol include the condensation of the carbonyl substrates and a nitroalkane in the presence of an ionic base, whiles this approach may lead to the Nef reaction and the Cannizzaro reaction. The methods utilizing Lewis acids as catalyst are quite attractive especially in view of its suppression of side reaction and application in asymmetic version of the reaction. However, Lewis acid catalysts used were often found to be water insoluble or water sensitive. Lewis acids that efficiently catalyzed Henry reaction in aqueous media have not been widely investigated although such catalysts would have important advantages related to environmental issues. We are interested in developing water-soluble Lewis acid catalysts having amino acids or its derivatives as ligands and to investigate their activities as recyclable catalysts for the Henry reaction. Herein we hope to report the Henry reaction catalyzed by a Zn-proline complex in the presence of water. The reactions proceeded smoothly at room temperature to produce 2-nitroalcohols with excellent yields and the catalyst can be reused repeatedly.Part 3. Phenolic acid esters motifs have widespread been found in bioactive natural products. In many cases, phenolic acid esters are also used as important intermediates for the medicine synthesis, although these compounds are structurally unsophisticated, their reported synthesis are typically suffer from a heavy burden of protecting groups for the purpose of...