2812-46-6Relevant articles and documents
Synthesis of the marine sponge cycloheptapeptide phakellistatin 51
Pettit, George R.,Toki, Brian E.,Xu, Jun-Ping,Brune, Daniel C.
, p. 22 - 28 (2000)
Phakellistatin 5 (1), a constituent of The Federated States of Micronesia (Chuuk) marine sponge Phakellia costada, was synthesized by solution-phase and solid-phase techniques. Because the linear peptide bearing (R)-Asn resisted cyclization, the synthesis of this peptide was repeated using the PAL resin attachment proceeding from N-Fmoc-D-Asp-α-OCH2CH=CH2. After addition of the final unit (Ala), the allyl ester was removed under neutral conditions with Pd°[P(C6H5)3l4. Removal of the final Fmoc- protecting group and cyclization with PyAOP provided (R)-Asn-phakellistatin 5 (2) in 28% overall yield. The same synthetic route from (S)-Asp led to natural phakellistatin 5 (1) in 15% overall recovery. The solution-phase and solid-phase synthetic products derived from (S)-Asp were found to be chemically but not biologically identical with natural phakellistatin 5 (1). This important fact suggested that a trace, albeit highly cancer-cell growth inhibitory, constituent accompanied the natural product or that there is a subtle conformational difference between the synthetic and natural cyclic peptides.
α-Sila-Dipeptides: Synthesis and Characterization
Minkovich, Boris,Ruderfer, Ilya,Kaushansky, Alexander,Bravo-Zhivotovskii, Dmitry,Apeloig, Yitzhak
, p. 13261 - 13265 (2018)
The first two α-sila-dipeptides, 7 and cyclo-sila-dipeptide 8, were synthesized and characterized by several methods, including X-ray crystallography. Bulky t-BuMe2Si substituents provide some kinetic stabilization to the synthesized molecules. 7 and 8 are the first examples of a “Si for C switch” in the central α-position of an amino acid or a peptide, in which silicon is bonded to both the amino and the carbonyl groups.
Structure, Total Synthesis, and Biosynthesis of Chloromyxamides: Myxobacterial Tetrapeptides Featuring an Uncommon 6-Chloromethyl-5-methoxypipecolic Acid Building Block
Gorges, Jan,Panter, Fabian,Kjaerulff, Louise,Hoffmann, Thomas,Kazmaier, Uli,Müller, Rolf
, p. 14270 - 14275 (2018)
Soil-living microbes are an important resource for the discovery of new natural products featuring great structural diversity that are reflective of the underlying biosynthetic pathways as well as incorporating a wide range of intriguing small-molecule building blocks. We report here the full structural elucidation, total synthesis, and biosynthesis of chloromyxamides, a new class of tetrapeptides that display an unprecedented 6-chloromethyl-5-methoxypipecolic acid (CMPA) substructure. Chemical synthesis—including an approach to access the CMPA unit—was pursued to confirm the structure of the chloromyxamides and enabled determination of the absolute configuration in the CMPA ring. A model for the nonribosomal assembly of chloromyxamides was devised on the basis of the combined evaluation of the biosynthetic gene cluster sequence and the feeding of stable isotope-labeled precursors. This provided insight into the formation of the various chloromyxamide derivatives and the biogenesis of the CMPA unit.
A General Stereocontrolled Synthesis of Opines through Asymmetric Pd-Catalyzed N-Allylation of Amino Acid Esters
Albat, Dominik,Neud?rfl, J?rg-Martin,Schmalz, Hans-Günther
supporting information, p. 2099 - 2102 (2021/07/22)
A stereo-divergent synthesis of natural and unnatural opines in stereochemically pure form is based on the direct palladium-catalyzed N-allylation of α-amino acid esters (up to 97 % ee or 99 : 1 d.r.) using methyl (E)-2-penten-4-yl carbonate in the presence of only 1 mol% of a catalyst, prepared in-situ from the C2-symmetric diphosphine iPr-MediPhos and [Pd(allyl)Cl]2. Selected target compounds (incl. a derivative of the drug enalapril) were efficiently obtained from the N-allylated intermediates by oxidative cleavage (ozonolysis) of the allylic C=C bond under temporary N-Boc-protection.
Continuous Flow Synthesis of ACE Inhibitors From N-Substituted l-Alanine Derivatives
Breen, Christopher P.,Jamison, Timothy F.
supporting information, p. 14527 - 14531 (2019/11/03)
A strategy for the continuous flow synthesis of angiotensin converting enzyme (ACE) inhibitors is described. An optimization effort guided by in situ IR analysis resulted in a general amide coupling approach facilitated by N-carboxyanhydride (NCA) activation that was further characterized by reaction kinetics analysis in batch. The three-step continuous process was demonstrated by synthesizing 8 different ACE inhibitors in up to 88 % yield with throughputs in the range of ≈0.5 g h?1, all while avoiding both isolation of reactive intermediates and process intensive reaction conditions. The process was further developed by preparing enalapril, a World Health Organization (WHO) essential medicine, in an industrially relevant flow platform that scaled throughput to ≈1 g h?1.
Ring-Strain Effects in Base-Induced Sommelet–Hauser Rearrangement: Application to Successive Stereocontrolled Transformations
Tayama, Eiji,Watanabe, Kazutoshi,Matano, Yoshihiro
, p. 3631 - 3641 (2016/07/29)
The base-induced Sommelet–Hauser (S–H) rearrangement of azetidine-2-carboxylic acid ester-derived ammonium salts into 2-aryl-substituted derivatives was demonstrated. The ring-strain of four-membered N-heterocycles enables efficient generation of the desired ylide intermediate and enhances the rate of the S–H rearrangement. The asymmetric version of the rearrangement was characterized by excellent levels of successive chirality transmissions. The regio- and stereo-controlled nucleophilic ring opening of the rearrangement products produced quaternary α-aryl amino acid esters with excellent enantiopurities.
Total synthesis of wewakazole B
Long, Bohua,Zhang, Jingzhao,Tang, Xudong,Wu, Zhengzhi
, p. 9712 - 9715 (2016/10/31)
Wewakazole B is a novel cyclodecapeptide with highly potent cytotoxic activity isolated from a sample of M. producens collected from the Red Sea. It contains nine common and three modified amino acid residues. The first total synthesis of Wewakazole B was successfully achieved on a gram scale, unambiguously confirming its structure. Notable features include the careful choice of amino acid-protecting groups and the construction of three different substituted oxazoles present in this natural product.
Stereoselective Synthesis of Tricyclic Diproline Analogues that Mimic a PPII Helix: Structural Consequences of Ring-Size Variation
Soicke, Arne,Reuter, Cédric,Winter, Matthias,Neud?rfl, J?rg-Martin,Schl?rer, Nils,Kühne, Ronald,Schmalz, Hans-Günther
supporting information, p. 6467 - 6480 (2016/02/18)
Polycyclic proline-derived scaffolds (ProMs) have recently demonstrated their value as conformationally defined dipeptide analogs for the modular construction of secondary structure mimetics, specifically interfering with PPII helix-mediated protein-protein interactions. We disclose the stereoselective synthesis of two new tricyclic amino acid scaffolds (ProM-4 and ProM-8) that differ from the first generation scaffold ProM-1 by the size of ring A. Conformational preferences and subtle structural differences of the three homologous scaffolds were analyzed by X-ray crystallography, computational calculations, and NMR spectroscopy. N-tert-butoxycarbonyl(Boc)-3-(1-propenyl)azetidine-2-carboxylic acid was prepared from L-aspartic acid through β-lactam intermediates. The corresponding piperidine-based building block rac-N-Boc-3-vinylpipecolic acid was synthesized by Cu-catalyzed 1,4-addition of vinyl-MgBr to methyl N-Boc-2,3-dehydropipecolate. Target molecules were prepared through peptide coupling of the respective ring A building blocks with cis-5-vinylproline tert-butyl ester and subsequent ring-closing metathesis. Selective deprotection of a tert-butyl carbamate (N-Boc protecting group) in the presence of a tert-butyl ester was achieved with trifluoroacetic acid at 0 C. Two new tricyclic amino acid scaffolds, which differ from the first generation scaffold by the size of ring A, were stereoselectively synthesized. The conformational analysis of the three homologous scaffolds was revealed by NMR spectroscopy.
Stereoselective synthesis of cyclic amino acids via asymmetric phase-transfer catalytic alkylation
Kano, Taichi,Kumano, Takeshi,Sakamoto, Ryu,Maruoka, Keiji
supporting information, p. 271 - 278 (2013/02/25)
An asymmetric synthesis of cyclic amino acids having piperidine and azepane core structures was realized starting from readily available glycine and alanine esters by combination of phase-transfer catalyzed asymmetric alkylation and subsequent reductive a
Solution-phase synthesis and evaluation of tetraproline chiral stationary phases
Dai, Zhi,Ye, Guozhong,Pittman Jr., Charles U.,Li, Tingyu
, p. 329 - 338 (2012/05/20)
A protocol was developed for the solution-phase synthesis of multigram amounts of two 9-fluorenylmethoxycarbonyl (Fmoc)-protected tetraproline peptides. These tetraproline peptides were then attached to amino derivatized silica gel. The replacement of the Fmoc group with the trimethylacetyl group lead to two tetraproline chiral stationary phases (CSPs). A comparison of the chromatographic behavior of these two solution-phase-synthesized tetraproline CSPs with that prepared by stepwise solid-phase synthesis revealed that all three had similar chromatographic performance for resolving 53 model analytes. This suggests that the solution-phase synthesis of oligoprolines, which allows for the specific benefits of good batch reproducibility, selector homogeneity, and possibly low cost, is a feasible alternative to the solid-phase synthesis of oligoproline CSPs. Copyright
