Refernces
10.1021/ol0157813
The study presents a novel strategy for synthesizing polypeptides using recombinant proteins, which are nonprotected peptides, in conjunction with S-alkyl peptide thioesters as building blocks. The method involves oxidizing the N-terminal serine of a peptide to form an Nr-glyoxyloyl peptide, which then undergoes reductive amination with 4,5-dimethoxy-2-(triphenylmethylthio)benzylamine to attach a thiol linker. This results in an Nr-4,5-dimethoxy-2-mercaptobenzyl glycyl peptide, which can be condensed with a peptide thioester to form a peptide bond. The innovative aspect of this approach is the use of the 4,5-dimethoxy-2-mercaptobenzyl (Dmmb) group as a linker, which can be removed under acidic conditions, allowing for the synthesis of peptides with native peptide bonds. The study demonstrates this method using a model sequence and shows the successful preparation of a thiol linker-attached peptide for condensation with peptide thioesters, providing a useful method for peptide synthesis in a neutral aqueous environment without the need for protecting groups.
10.1021/jo0626109
The research focuses on the synthesis of medium ring keto-lactones, which are significant in organic synthesis due to their presence in many natural products. The study employs bicyclic δ-hydroxytetrahydrofurans as precursors and utilizes ruthenium tetraoxide (RuO4) for their oxidative cleavage, yielding 9- and 10-membered keto-lactones with moderate to good yields. The precursors were obtained through two alternative procedures: epoxidation by dimethyldioxirane followed by base-catalyzed cyclization, or thallium trinitrate-mediated cyclization. The experiments involved the use of ruthenium trichloride and sodium periodate to generate RuO4 in situ, and the oxidative cleavage was conducted in a biphasic solvent system. The analysis of the resulting keto-lactones was performed using techniques such as gas chromatography (GC), infrared (IR) spectroscopy, low-resolution mass spectrometry (LRMS), and nuclear magnetic resonance (NMR) spectroscopy, which provided detailed information on the structure and composition of the synthesized compounds.
10.1021/jo00060a040
The research focuses on the cleavage of unsaturated α-ketols to o-oxo-α,β-unsaturated acids, with the aim of developing an enantioselective synthesis of cyclic systems bearing contiguous quaternary centers, particularly those with gem-dimethyl groups. The study concludes that sodium periodate is the most effective reagent for this cleavage, outperforming other common oxidizing agents like sodium bismuthate, manganese dioxide, and lead tetraacetate, in terms of yield and efficiency. The combination of this cleavage reaction with a rhodium(I)-mediated decarbonylation of o-oxo-α,β-unsaturated esters derived from polycyclic systems was found to be a successful approach for the synthesis of the desired cyclic systems. Key chemicals used in the process include sodium periodate, sodium bismuthate, manganese dioxide, lead tetraacetate, and various α-ketols, among others, with the research providing detailed procedures and spectral data for the synthesized compounds.
10.1246/cl.1984.1427
The research focuses on the development of a convenient method for synthesizing vinyl ketones using a new three-carbon homologating agent, 4-phenylthio-N,N-dimethylaminobutyronitrile. The purpose of this study was to explore the synthetic potential of this reagent as an acyl anion equivalent in organic chemistry. The researchers demonstrated the effectiveness of this agent by generating lithio compounds through reactions with lithium diisopropylamide (LDA) in tetrahydrofuran (THF) at low temperatures. These lithio compounds were then subjected to alkylation with halides and addition reactions with carbonyl compounds, yielding γ-keto sulfides. The γ-keto sulfides were subsequently oxidized using sodium metaperiodate or m-chloroperbenzoic acid (MCPBA) to form γ-keto sulfoxides, which were then pyrolyzed to produce vinyl ketones in high yields.