Conjugate allylation reactions of alkylidene malononitriles mediated by NHC-ligated palladium catalysts
摘要:
Conjugate allylation of malononitriles is reported using catalytic N-heterocyclic carbene-ligated palladium complexes. This conjugate allylation reaction yields a variety of monoallylated products. These results contrast the bis-allylation of malononitriles using other palladium-based catalysts. This reaction tolerates a wide variety of functional groups including aryl groups, heteroaromatics, and aliphatic substituents to provide the desired products in good to excellent yields. Derivativation of the monoallylation products to form a triamino pyrimidine is demonstrated. (C) 2008 Elsevier Ltd. All rights reserved.
Direct addition of alkylzirconocenes to activatedalkenes was found, for the first time. Octyl- and decylzirconocene chloride reacted with benzylidenemalononitrile to give the corresponding addition products after hydrolysis in 86% and 79% yield, respectively. Zirconacyclopentanes showed a similar reactivity toward activatedalkenes with a two-electron-withdrawing group. On the other hand, treatment
Visible‐Light Photoredox‐Catalyzed α‐Regioselective Conjugate Addition of Allyl Groups to Activated Alkenes
作者:Arjun Gontala、Sang Kook Woo
DOI:10.1002/adsc.202000445
日期:2020.8.4
The α‐regioselective conjugate addition of allyl groups to activated alkenes is a poorly explored area of research. Herein, we report an α‐adduct and (E )‐isomer selective conjugate addition of allylsilanes to activated alkenes by visible‐light photoredox catalysis. The reaction involves allylic radicals that can be generated from allylsilanes through a photoinduced single‐electron transfer mechanism
Irradiation of 1-aryl-2,2-dicyanoethenes and tetraalkylstannanes in propionitrile in the presence of phenanthrene afforded regioselectively 1-alkyl-1-aryl-2,2-dicyanoethanes in good yields.
Visible‐Light‐Mediated Regioselective Allylation, Benzylation, and Silylation of Methylene‐Malononitriles via Photoredox‐Induced Radical Cation Fragmentation
Visible‐light‐mediated regioselevtive allylation, benzylation, and silylation of methylene‐malononitriles with silanes have been realized. The reactions proceed via a photoredox‐catalyzed σ‐C–Si+· or σ‐Si–Si+· type radical cation fragmentation.
Dual Regioselectivity in the Photoallylation of Electron-Deficient Alkenes by Allylic Silanes
作者:Kazuhiko Mizuno、Munehiro Ikeda、Yoshio Otsuji
DOI:10.1246/cl.1988.1507
日期:1988.9.5
The photoreaction of 1-aryl-2,2-dicyanoethenes with allylic silanes in the presence of phenanthrene gave 4-aryl-5,5-dicyano-1-pentenes in high yields. In this photoreaction, the allylic groups were introduced regioselectively at the β-position to cyano group. In contrast, the photoreaction of alkylidenepropanedinitriles with allylic silanes gave products allylated at the α-position to cyano group along with their reduction products.