route to a small family of exotic marine alkaloids known as the araiosamines has been developed, and their absolute configuration has been assigned. The dense array of functionality, high polarity, and rich stereochemistry coupled with equilibrating topologies present an unusual challenge for chemical synthesis and an opportunity for innovation. Key steps involve the use of a new reagent for guanidine installation
Polymer-Supported Hantzsch 1,4-Dihydropyridine Ester: An Efficient Biomimetic Hydrogen Source for the Reduction of Ketimines and Electron-Withdrawing Group Conjugated Olefins
作者:Jun Che、Yulin Lam
DOI:10.1002/adsc.201000093
日期:——
A polymer‐supported Hantzsch 1,4‐dihydropyridine ester was observed to be a useful selective reducing agent for the reduction of ketimines and electron‐withdrawing conjugatedolefins. The rate of the reduction of electron‐withdrawing conjugatedolefins is dependent on the nature of the conjugated substituents and could be enhanced by microwave irradiation. The reduction of (Z)‐α‐cyano‐β‐bromomethylcinnamates
Transition-Metal-Free Radical C(sp<sup>3</sup>)–C(sp<sup>2</sup>) and C(sp<sup>3</sup>)–C(sp<sup>3</sup>) Coupling Enabled by 2-Azaallyls as Super-Electron-Donors and Coupling-Partners
作者:Minyan Li、Simon Berritt、Lucas Matuszewski、Guogang Deng、Ana Pascual-Escudero、Grace B. Panetti、Michal Poznik、Xiaodong Yang、Jason J. Chruma、Patrick J. Walsh
DOI:10.1021/jacs.7b09394
日期:2017.11.15
and alkyl radicals. The SET process converts the 2-azaallyl anions into persistent 2-azaallyl radicals, which capture the aryl and alkyl radicals to form C-C bonds. The radicalcoupling of aryl and alkyl radicals with 2-azaallyl radicals makes possible the synthesis of functionalized amine derivatives without the use of exogenous radicalinitiators or transition metal catalysts. Radical clock studies
过去十年见证了自由基生成策略及其在CC成键反应中的应用的快速发展。大多数这些过程需要引发剂、过渡金属催化剂或有机金属试剂。在此,我们报告了一种简单的有机系统(2-氮杂烯丙基阴离子)的发现,该系统可以在无过渡金属的条件下实现自由基偶联反应。N-苄基酮亚胺的去质子化产生半稳定的 2-氮杂烯丙基阴离子,其充当“超级电子给体”(SED),并将芳基碘和烷基卤还原为芳基和烷基。SET 过程将 2-氮杂烯丙基阴离子转化为持久的 2-氮杂烯丙基自由基,捕获芳基和烷基自由基形成 CC 键。芳基和烷基与2-氮杂烯丙基的自由基偶联使得在不使用外源自由基引发剂或过渡金属催化剂的情况下合成官能化胺衍生物成为可能。自由基时钟研究和 2-氮杂烯丙基阴离子偶联研究为这种独特的反应性提供了机制见解。
A Flexible Approach toward Trisubstituted Piperidines and Indolizidines: Synthesis of 6-<i>e</i><i>pi</i>-Indolizidine 223A
作者:Joel M. Harris、Albert Padwa
DOI:10.1021/jo034324s
日期:2003.5.1
subsequent addition of various nucleophiles to a transient N-sulfonyliminium ion. The stereochemistry of the conjugate addition product is the result of axialattack from the face opposite the diaxial substituents at C(2) and C(6). This can be attributed to steric hindrance between the pseudoaxially oriented 2,6-substituents and the equatorially approaching nucleophile, thereby leading to the exclusive
Synthesis of New Spiropyrrolidines and Michael Addition Products Using Phase Transfer Catalyzed Addition of Schiff Bases to 9-Arylmethylenefluorenes
作者:Kostadinka Popandova-Yambolieva
DOI:10.1135/cccc19940489
日期:——
As a continuation of our previous studies concerned with the reactivity of benzylidene- and furfurylidenefluorenes in addition reactions, in the present work we have prepared a series of new spiropyrrolidines by reactions of 9-arylmethylenefluorenes I with aryl- (II) and furylazomethines (IV) and some Michael addition products by using diphenylmethyleneazomethines VI and VIII. The structure B was assigned to the furylspiropyrrolidines Va - Vf based on 1H NMR data.