Refernces
10.1021/jo961653u
The study focuses on the total synthesis of (±)-dihydrokawain-5-ol, a unique natural product isolated from the kava plant (Piper methysticum). The synthesis begins with a highly diastereoselective iodocyclofunctionalization of α-allenic alcohols to produce vinyl iodo syn-vicinal diols. A key feature of the synthesis is the differentiation of the alcohol groups in the vicinal diols through selective monoprotection using methoxymethyl (MOM) ethers or silyl ethers, followed by further functional group manipulations. The work explores various regioselective monoprotection techniques, cyclization strategies, and the isomerization of intermediates to form the final dihydropyranone structure found in dihydrokawain-5-ol. The study exemplifies the challenges and solutions in synthesizing complex natural products with specific stereochemical requirements.
10.1021/ja904604x
The research focuses on the total synthesis and structure-activity investigation of the marine natural product neopeltolide, a highly cytotoxic compound with potential anticancer properties. The study employs a key bond-forming step using Lewis acid-catalyzed intramolecular macrocyclization to simultaneously install a tetrahydropyran ring and a macrocycle. The researchers synthesized neopeltolide and its analogs to evaluate their biological activity against cancer cell lines, finding that neither the macrolide nor the oxazole side chain alone could inhibit cancer cell growth, but alterations to the ester side chain or macrolide stereochemistry resulted in a loss of biological activity. The synthesis involved various reactants, including 1,3-propanediol, ethyl 3-oxohexanoate, and methyl chloroformate, and utilized techniques such as Ti(i-OPr)4-catalyzed aldol reactions, Noyori reduction, and Stille coupling. The synthesized compounds were analyzed using 1D and 2D NMR spectroscopy, HRMS, and optical rotation to confirm their structures and assess their biological activity through cell proliferation assays.
10.1002/jhet.5570320532
The research focuses on the synthesis and reactivity of N-protected pyroglutamic derivatives, specifically pyroglutamoyl chlorides N-protected by a methoxycarbonyl or a trifluoroacetyl group. The purpose of this study was to develop an easy and convenient synthesis method for these unstable compounds and to explore their reactivity, with the aim of overcoming stability issues and simplifying the deprotection process. The researchers successfully synthesized N-trifluoroacetyl and N-methoxycarbonyl pyroglutamoyl chlorides and studied their reactions with various reagents, including methanol, thionyl chloride, trifluoroacetic anhydride, and methyl chloroformate. They also investigated the condensation of these derivatives with aromatic amines and their reactions with isopropylidene malonate (Meldrum's acid). The study concluded that the protecting groups could be easily removed without opening the lactam ring, and the reactions were effectively monitored using proton nuclear magnetic resonance (1H NMR). The chemicals used in the process included pyroglutamic acid, trifluoroacetic anhydride, methyl chloroformate, thionyl chloride, and various amines, among others.
10.1021/jo0013711
The research focuses on the asymmetric synthesis of (S)-CPPG, a selective antagonist for group III metabotropic glutamate receptors (mGluRs), which are important in studying neurotransmission mechanisms. The synthesis begins with (R)-4-benzoxyphenylglycine and involves several steps including protection of the amino group, formation of trans-oxazolidinone, introduction of a dicarbon functional group, and cyclopropanation. Key reactants include methyl chloroformate, benzaldehyde dimethyl acetal, boron trifluoride etherate, and various catalysts for cyclopropanation. The process involves recrystallization, HPLC, and 1H NMR for analysis, and culminates in the production of (S)-CPPG with a final yield of 99% after purification. The study also mentions the biological evaluation of the synthesized compound, indicating ongoing research into its physiological effects.
10.1039/jr9640001727
The study investigates the reactions of aromatic nitro-compounds, specifically picramide (PicNH?) and its NN-dimethyl derivative (PicNMe?), in aqueous sodium hydroxide solutions. Picramide and dimethylpicramide both react with hydroxide ions to form soluble complexes. Picramide forms a 1:1 complex with hydroxide ions, while dimethylpicramide forms a 1:2 complex. The equilibrium constants for these reactions were measured. The study also examines the kinetics of the reactions, including the slow, irreversible hydrolysis that leads to the formation of picrate ions. In the presence of visible light, additional reactions occur, resulting in the formation of nitrite ions and a mixture of 3,5-dinitrocatechol and 2,6-dinitroquinone. The rates of these reactions were measured as a function of hydroxide ion concentration. The study aims to understand the behavior of these compounds in alkaline media and the nature of the complexes formed.
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