نتایج جستجو برای: diastereoselective synthesis
تعداد نتایج: 409824 فیلتر نتایج به سال:
The asymmetric synthesis of enantiopure pyrrolidines is reported via a streamlined strategy relying on two sequential C?H functionalizations simple hydrocarbons. first step regio- and stereoselective catalytic nitrene insertion. Then, subsequent diastereoselective cyclization involving 1,5-hydrogen atom transfer (HAT) from N-centered radical leads to the formation that can then be converted the...
A versatile nitro-Mannich/lactamisation cascade for the direct stereoselective synthesis of heavily decorated 5-nitropiperidin-2-ones and related heterocycles has been developed. A highly enantioenriched substituted 5-nitropiperidin-2-one was synthesised in a four component one-pot reaction combining an enantioselective organocatalytic Michael addition with the diastereoselective nitro-Mannich/...
We report on a diastereoselective synthesis of six derivatives of caffeoyl- and feruloyl-muco-quinic acids. All the muco-quinic acid derivatives were obtained in excellent yield in five steps starting from quinic acid, caffeic acid and ferulic acid. Allyl ether protection of trans-hydroxy cinnamic acids was here introduced to chlorogenic acids synthesis. We show that muco-quinic acid derivative...
[reaction: see text] We describe the diastereoselective synthesis of a pharmaceutically active drug candidate via a column-based system. This methodology is complementary to classical solid-phase synthesis; individual columns are packed with resin-bound reagents and then linked in sequence and/or in parallel. In contrast to the traditional solid-phase approach, substrates are introduced in the ...
We document a route for the synthesis of a densely functionalized spiro-fused 2,5-cyclohexadienone as an intermediate for the synthesis of resineferatoxin. The strategy is based on an unprecedented diastereoselective, intramolecular phenol para-alkylation to a cross-conjugated cyclohexadienone. In the course of these synthetic studies we developed rapid access to a chiral nitrile possessing a q...
[reaction: see text] The enantioselective synthesis of the (+)-leucascandrolide A macrolactone has been achieved in 20 linear steps from 1,3-propanediol. The key steps in the synthesis are a reductive cleavage of bicyclic ketal 5 to establish the C15 stereogenic center and a diastereoselective aldol of the boron enolate of methyl ketone 3 to aldehyde 4 in preparation for a heteroconjugate addit...
A domino reaction has been developed for the synthesis of oxygen bridged bicyclic ethers through the coupling of 4-(2-hydroxyethyl)cyclohex-3-enols with aldehydes in the presence of 10 mol% of molecular iodine in dichloromethane at 25 °C. This method is highly diastereoselective affording the corresponding bicyclic ethers, i.e. octahydro-4a,7-epoxyisochromenes in good yields with high selectivi...
Metal-free and environmentally friendly synthesis highly controlled by natural sources like visible light and air (or oxygen) is always a pursuit of green chemistry. In this paper, an atmosphere and light tuned highly diastereoselective synthesis of two important polyheterocyclic skeletons: cyclobuta/penta[b]indoles from aniline-tethered alkylidenecyclopropanes with alkynes, has been developed....
Abstract A method for the synthesis of functionalized piperidines containing 3 contiguous stereocentres in 2-,3- and 4- positions uses a diastereoselective nitro-Mannich to control stereochemistry. The reaction between β-aryl/heteroaryl substituted nitroalkanes glyoxylate imine provides β-nitro-amines with good selectivity (70:30 >95:5) syn, anti-diastereoisomers. Reductive cyclisation BF3.OEt2...
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