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121.
A cycloheptapeptide cyclo(Gly-Tyr-Gly-Gly-Pro-Phe-Pro), which was isolated and identified from one kind of Chinese medicinal herbs, was chosen as a model cyclopeptide, to evaluate an organophosphorus reagent, 3-(diethyloxyphosphoryloxy)-1,2,3-benzotriazin-4(3H)-one(DEPBT) for synthesis of cyclopeptide and compared with two other organophosphorus reagents, DPPA and BOP. 相似文献
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Deiana L Dziedzic P Zhao GL Vesely J Ibrahem I Rios R Sun J Córdova A 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(28):7904-7917
The development, scope, and application of the highly enantioselective organocatalytic aziridination of α,β-unsaturated aldehydes is presented. The aminocatalytic azirdination of α,β-unsaturated aldehydes enables the asymmetric formation of β-formyl aziridines with up to >19:1 d.r. and 99% ee. The aminocatalytic aziridination of α-monosubstituted enals gives access to terminal α-substituted-α-formyl aziridines in high yields and up to 99% ee. In the case of the organocatalytic aziridination of disubstituted α,β-unsaturated aldehydes, the transformations were highly diastereo- and enantioselective and give nearly enantiomerically pure β-formyl-functionalized aziridine products (99% ee). A highly enantioselective one-pot cascade sequence based on the combination of asymmetric amine and N-heterocyclic carbene catalysis (AHCC) is also disclosed. This one-pot three-component co-catalytic transformation between α,β-unsaturated aldehydes, hydroxylamine derivatives, and alcohols gives the corresponding N-tert-butoxycarbonyl and N-carbobenzyloxy-protected β-amino acid esters with ee values ranging from 92-99%. The mechanisms and stereochemistry of all these catalytic transformations are also discussed. 相似文献
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当用DEPBT作为缩合试剂合成含组氨酸的肌肽(β-Ala-His)衍生物时, 又偶然发现了另一个副反应. 在这个反应中, 没有得到预期的肌肽产物, 而是生成了一个结构与DEPBT相关的副产物EODhbt(3-乙氧基-3,4-二氢-1,2,3-苯并三嗪-4-酮). 本文报道了此副产物的发现、 结构鉴定及影响副反应的各种因素. 这对深入了解DEPBT的反应特性, 并且在含组氨酸的多肽合成中更有效地应用DEPBT提供了有用的信息. 相似文献