Esterolytic abzymes were generated via immunization with a haptenic diphosphonate mounted with two distinct traps actuated by the "bait and switch" and "transition-state mimic" concepts. One monoclonal antibody, 12F12, was characterized in detail, and showed significant rate enhancement and unique substrate specificity. Experimental data support that the antibody catalyzes the reactions with a concerted catalytic mechanism. (C) 1999 Elsevier Science Ltd. All rights reserved.
A New Method for Efficient Coupling of Indole and Epoxide Catalyzed with Yb(OTf)3, and Application to the Total Synthesis of Kurasoin B
stereoselective synthesis of tetracyclic intermediate, the indoline spiroaminal 3 for neoxaline (1) and oxaline (2), has been accomplished. The key step of the stereoselective synthesis of 3 was the Lewis acid mediated transcyclization of 4 to the diaminal 18, and the tungstate-catalyzed oxidation of 18 to obtain the nitrone 19, which easily cyclizes to the indoline spiroaminal framework 3. [structure:
作者:Thang Loi Pham、Patcharaporn Sae-Lao、Hannah Hui Min Toh、Dániel Csókás、Roderick W. Bates
DOI:10.1021/acs.joc.2c02033
日期:2022.12.2
The total synthesis of raistrickindole A has been achieved, thereby confirming the proposedstructure as an N-hydroxylated DKP. In the first but less selective approach, the DKP was built up by cyclization of a diastereoisomerically mixed N-hydroxylated dipeptide. In the second approach, the same DKP was constructed stereoselectively by the intramolecular Mitsunobu reaction of a hydroxamic acid. The
已经实现了 raistrickindole A 的全合成,从而证实了所提出的结构为N-羟基化 DKP。在第一种但选择性较低的方法中,DKP 是通过非对映异构混合的N-羟基化二肽的环化作用构建的。在第二种方法中,相同的 DKP 是通过异羟肟酸的分子内 Mitsunobu 反应立体选择性地构建的。合成通过立体选择性氧化环化完成。