Highly stereoselective kinetic resolution of α-allenic alcohols: an enzymatic approach
作者:Wenhua Li、Zuming Lin、Long Chen、Xuechao Tian、Yan Wang、Sha-Hua Huang、Ran Hong
DOI:10.1016/j.tetlet.2015.12.098
日期:2016.2
A highly efficient lipase AK-catalyzed direct kinetic resolution of a variety of α-allenic alcohols was developed. With the complementary to previous studies, the current reaction system is effective on a broad range of substituents (R1) at C(1), such as alkyl, aryl, alkenyl, and alkynyl groups. The Jones–Burgess empirical model was modified to interpret the reversed selectivity during the acetylation
with azomethineimines has successfully been developed under mild reaction conditions, affording biologically interesting tetrahydropyrazoloisoquinoline derivatives in high to excellent yields and with excellent stereoselectivity. The reaction follows a tandem [3+2] cycloaddition/allylation/elimination of AcOH pathway. Allenyl carbinol acetates also reacted well with in situ generated azomethine imine
Regioselectivity Switch in Palladium‐Catalyzed Allenylic Cycloadditions of Allenic Esters: [4+1] or [4+3] Cycloaddition/Cross‐Coupling
作者:Long Li、Pengfei Luo、Yuhua Deng、Zhihui Shao
DOI:10.1002/anie.201901511
日期:2019.3.26
The first Pd‐catalyzed asymmetric allenylic [4+1] cycloaddition was successfully developed. Alternatively, tuning the Pd catalyst switched the reactivity toward an unprecedented [4+3] cycloaddition/cross‐coupling. Ligands play a vital role in controlling the reaction pathway, allowing highly selective access to different products from identical substrates. Biological evaluation of the obtained compounds
1,4-Iron Migration for Expedient Allene Annulations through Iron-Catalyzed C−H/N−H/C−O/C−H Functionalizations
作者:Jiayu Mo、Thomas Müller、João C. A. Oliveira、Lutz Ackermann
DOI:10.1002/anie.201801324
日期:2018.6.25
C−H activation bears great potential for enabling sustainable molecular syntheses in a step‐ and atom‐economical manner, with major advances having been realized with precious 4d and 5d transition metals. In contrast, we employed earth abundant, nontoxic iron catalysts for versatile allene annulations through a unique C−H/N−H/C−O/C−Hfunctionalization sequence. The powerful iron catalysis occurred
Rh(<scp>iii</scp>)-Catalyzed [5 + 1] annulation of 2-alkenylanilides and 2-alkenylphenols with allenyl acetates
作者:Anurag Singh、Rahul K. Shukla、Chandra M. R. Volla
DOI:10.1039/d1sc06097j
日期:——
Herein, we report a mild and highly regioselective Rh(III)-catalyzed non-oxidative [5 + 1] vinylic C–H annulation of 2-alkenylanilides with allenyl acetates, which has been elusive so far. The reaction proceeds via vinylic C–H activation, regioselective 2,3-migratory insertion, β-oxy elimination followed by nucleophilic cyclization to get directaccess to 1,2-dihydroquinoline derivatives. The strategy
在此,我们报道了一种温和且高度区域选择性的Rh( III )催化的2-烯基苯胺与乙酸丙二烯酯的非氧化[5+1]乙烯基C-H成环反应,迄今为止该反应还难以实现。该反应通过乙烯基 C-H 活化、区域选择性 2,3-迁移插入、β-氧基消除,然后进行亲核环化,直接生成 1,2-二氢喹啉衍生物。该策略还成功扩展到 2-烯基酚的 C-H 活化,以构建色烯衍生物。在整个[5+1]环化中,丙二烯充当一个碳单元。人们发现丙二烯上的乙酸基对于控制反应的区域选择性和化学选择性以及促进β-氧基消除都至关重要。该方法具有可扩展性,并进一步扩展到各种天然产物的后期功能化。