Enantioselective Synthesis of Cyclopentene Carbaldehydes by a Direct Multicatalytic Cascade Sequence: Carbocyclization of Aldehydes with Alkynes
作者:Kim L. Jensen、Patrick T. Franke、Carlos Arróniz、Sara Kobbelgaard、Karl Anker Jørgensen
DOI:10.1002/chem.200903405
日期:2010.2.8
A multicatalytic, asymmetric cascade reaction sequence of α,β‐unsaturated aldehydes with alkyne‐tethered nucleophiles has been developed. Organocatalytic iminium–enamine catalysis combined with Lewis acid alkyne activation gave cyclopentenecarbaldehyde products in good yields and excellent stereoselectivities (see scheme). To highlight the potential of the sequence, a key structure for the preparation
double‐activation strategy for α′‐alkylidene cyclic enone substrates that uses a chiral primary amine and 2‐mercaptobenzoic acid to promote regio‐ and chemoselective addition to generate the complex interrupted iminium ion species. Significantly enhanced reactivity and enantioselectivity were observed for β‐regioselective Michael addition and Friedel–Crafts alkylation with malononitriles and indoles, respectively
Mn-Catalyzed Electrochemical Chloroalkylation of Alkenes
作者:Niankai Fu、Yifan Shen、Anthony R. Allen、Lu Song、Atsushi Ozaki、Song Lin
DOI:10.1021/acscatal.8b03209
日期:2019.1.4
The heterodifunctionalization of alkenes is an efficient method for synthesizing highly functionalized organic molecules. In this report, we describe the use of anodically coupled electrolysis for the catalytic chloroalkylation of alkenes—a reaction that constructs vicinal C–C and C–Cl bonds in a single synthetic operation—from malononitriles or cyanoacetates and NaCl. Knowledge of the persistent radical
Gold-Catalyzed 5- and 6-exo-dig Selective Cyclizations of Alkynyl Silyl Enol Ethers: Efficient Method for [3+2] and [4+2] Annulations onto α,β-Enones
作者:Kooyeon Lee、Phil Ho Lee
DOI:10.1002/adsc.200700304
日期:2007.9.3
An efficient method for the annulation of five- and six-membered rings onto α,β-enones is described via gold-catalyzed 5- and 6-exo-dig selective cyclizations of alkynyl silyl enolethers.
Optically Active Bicyclic N-Heterocycles by Organocatalytic Asymmetric Michael Addition/Cyclization Sequences
作者:Dennis Worgull、Gustav Dickmeiss、Kim L. Jensen、Patrick T. Franke、Nicole Holub、Karl Anker Jørgensen
DOI:10.1002/chem.201100233
日期:2011.4.4
Highly stereoselective one‐pot syntheses of various opticallyactive N‐heterocyclic bicycles have been developed. The protocols are based on an organocatalytic, asymmetric Michael addition followed by a condensation/cycloaddition sequence to furnish aziridine carbonyls, β‐lactams, or octahydrobenzo[c]isoxazoles depending on the reaction conditions and applied nucleophiles.
已开发出各种光学活性N杂环自行车的高度立体选择性单锅合成器。该方案基于有机催化,不对称迈克尔加成,然后进行缩合/环加成序列,以根据反应条件和所应用的亲核试剂提供氮丙啶羰基,β-内酰胺或八氢苯并[ c ]异恶唑。