共查询到20条相似文献,搜索用时 15 毫秒
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Thomas Ziegler Gregor Lemanski 《Angewandte Chemie (International ed. in English)》1998,37(22):3129-3132
The choice of activator is decisive for whether the α-(1→4)-linked disaccharide 2 α or the anomeric compound 2 β is formed from the prearranged glycoside 1 . Other β-mannosylsaccharides can also be synthesized selectively by intramolecular glycosylation. Bn=benzyl, Bz=benzoyl, MeOTf= methyl trifluoromethanesulfonate, NIS=N-iodosuccinimide. 相似文献
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A new approach to the synthesis of α,β-unsaturated ketones from 1,2,3-trimethyl benzimidazolium salt via the condensation reaction with aldehydes followed by the addition reaction of Grignard reagents with quaternary C=N bond was provided. 相似文献
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《Journal of heterocyclic chemistry》2018,55(8):1986-1990
An efficient and versatile linear synthesis of γ‐butyrolactone subunit of polycavernolide A has been reported in 14.2% overall yield with 10 linear steps by employing Sharpless asymmetric epoxidation, ring‐closing metathesis, and diastereoface selective hydrogenation. 相似文献
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Hydromagnesiation of silylarylacetylenes 1 in diethyl ether gave(E)-β-silylvinyl Grignard reagents 2,whichreacted with trialkylstannyl chlorides 3 to afford stereoselectively(E)-β-silylvinylstannanes 4 in good yields. 相似文献
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A novel method for the asymmetric synthesis of α,β‐diamino acids by using the 2,3,4,6‐tetra‐O‐pivaloyl‐β‐D ‐glucopyranosyl group (Piv4Glc) as chiral auxiliary was developed (Table and Scheme). The reaction was promoted by CuBr?Me2S as Lewis acid, and high yields and good diastereoselectivities were achieved. 相似文献
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Bartomiej Furman Ren Thürmer Zbigniew Kaua Robert ysek Wolfgang Voelter Marek Chmielewski 《Angewandte Chemie (International ed. in English)》1999,38(8):1121-1123
Despite the antibiotic activity and the attractiveness of β-lactams, the solid-phase synthesis of this class of compounds has been barely reported. Now the diastereoselective synthesis of the 1-oxacepham 2 from the resin-bound β-lactam derivative 1 has been achieved in five steps. The synthesis of 2 and other 1-oxacephams is attractive because all the reaction steps proceed in high yield, the purity of the product is high, and the reaction sequence is simple. 相似文献
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Lisa Ngu Debarpita Ray Samantha S. Watson Penny J. Beuning Mary Jo Ondrechen George A. ODoherty 《Molecules (Basel, Switzerland)》2022,27(8)
A diastereoselective synthesis of the β-anomer of glycinamide ribonucleotide (β-GAR) has been developed. The synthesis was accomplished in nine steps from D-ribose and occurred in 5% overall yield. The route provided material on the multi-milligram scale. The synthetic β-GAR formed was remarkably resistant to anomerization both in solution and as a solid. 相似文献
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Faizulla G. Kathawala Bernhard Prager Kapa Prasad Oljan Repi
Michael J. Shapiro Russell S. Stabler Leo Widler 《Helvetica chimica acta》1986,69(4):803-805
The reduction of δ-hydroxy-β-ketoesters 1 was investigated with three different reducing agents. In several instances, high selectivity in favor of syn-1,3-diols was observed. 相似文献
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A simple and efficient synthesis of functionalized β‐chlorohydrins is described from the regio‐ and stereoselective reaction of α‐epoxyketones with AlCl3 in acetonitrile at room temperature. 相似文献
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Stereoselective Organocatalyzed Synthesis of α‐Fluorinated β‐Amino Thioesters and Their Application in Peptide Synthesis 下载免费PDF全文
Dr. Jakub Saadi Dr. Marc‐Olivier Ebert Prof. Dr. Helma Wennemers 《Angewandte Chemie (International ed. in English)》2016,55(42):13127-13131
α‐Fluorinated β‐amino thioesters were obtained in high yields and stereoselectivities by organocatalyzed addition reactions of α‐fluorinated monothiomalonates (F‐MTMs) to N‐Cbz‐ and N‐Boc‐protected imines. The transformation requires catalyst loadings of only 1 mol % and proceeds under mild reaction conditions. The obtained addition products were readily used for coupling‐reagent‐free peptide synthesis in solution and on solid phase. The α‐fluoro‐β‐(carb)amido moiety showed distinct conformational preferences, as determined by crystal structure and NMR spectroscopic analysis. 相似文献