نتایج جستجو برای: Orthoesters
تعداد نتایج: 89 فیلتر نتایج به سال:
Propargyl 1,2-O-orthoesters are exploited for the synthesis of 1,2-trans O-glycosides of protected amino acids. N-Fmoc- and N-Cbz protected serine/threonine - benzyl/methyl esters reacted well with glucosyl-, galactosyl-, mannosyl- and lactosyl- derived propargyl 1,2-orthoesters affording respective 1,2-trans glycosides in good yields under AuBr(3)/4 Å MS Powder/CH(2)Cl(2)/rt. t-Boc serine deri...
Reversible covalent reactions have become an important tool in supramolecular chemistry and materials science. Here we introduce the acid-catalyzed exchange of O,O,O-orthoesters to the toolbox of dynamic covalent chemistry. We demonstrate that orthoesters readily exchange with a wide range of alcohols under mild conditions and we disclose the first report of an orthoester metathesis reaction. W...
High molecular weight sugar poly(orthoesters) were synthesized through reverse anomeric effect (RAE). We demonstrated that when RAE-enabled promoters, such as 4-(dimethylamino)pyridine (DMAP), triphenylphosphine (TPP) or imidazole, were employed, efficient polymerizations were achieved, giving sugar poly(orthoesters) with molecular weights up to 18 kDa.
The identification of cross-over products in the rearrangement of two structurally similar sugar 1,2-orthoesters to glycosidic products is reported.
We demonstrate stereolithographic 3D printing of pure aliphatic poly(ether esters) from spiro-orthoesters with near-net-zero shrinkage and significantly reduced stress.
Nine new phragmalin-type limonoid orthoesters, tabulalides F-N (1-9), together with three known compounds, tabulalides C and D, and tabularisin N (10-12), were isolated from the stem bark of Chukrasia tabularis var. velutina. Extensive spectroscopic technologies were applied to elucidate the structures of these new compounds, including the application of circular dichroism (CD) exciton chiralit...
The synthesis and polymerizability of atom-bridged bicyclic monomers was surveyed. The monomers included lactams, ureas, urethanes, lactones, carbonates, ethers, acetals, orthoesters, and amines. Despite widely-varying structures, they almost all polymerized to give polymers with monocyclic rings in the chain. The polymerizations are grouped by mechanism: uncoordinated anionic, coordinated anio...
Palladium(II) catalyzed carbonylation of 1-ethynyl-1-propargyl acetate is described; in the absence of the bisoxazoline (box) ligand, the second triple bond did not react, affording cyclic orthoesters and . The use of meso-Phbox-Pd(ii) strikingly changed the course of the reaction, yielding bicyclic lactone by tandem carbonylative cyclization as a result of insertion of the second triple bond.
The first stereoselective version of an iodine(III)-mediated rearrangement of arylketones in the presence of orthoesters is described. The reaction products, α-arylated esters, are very useful intermediates in the synthesis of bioactive compounds such as ibuprofen. With chiral lactic acid-based iodine(III) reagents product selectivities of up to 73 % ee have been achieved.
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