Dual Iminium- and Lewis Base Catalyzed Morita–Baylis–Hillman Reaction on Cyclopent-2-enone

Synlett ◽  
2017 ◽  
Vol 29 (06) ◽  
pp. 820-824 ◽  
Author(s):  
Andrea Trabocchi ◽  
Riccardo Innocenti ◽  
Gloria Menchi
Keyword(s):  
Experimental Evidence ◽  
Lewis Base ◽  
Secondary Amines ◽  
Nucleophilic Attack ◽  
Allylic Alcohols ◽  
Base Catalyst ◽  
Co Catalysts

The application of iminium catalysis to the challenging Morita–Baylis–Hillman reaction on cyclopenten-2-one leads to the corresponding allylic alcohols in excellent yields. Experimental evidence shows that secondary amines act as co-catalysts activating the enone moiety towards the nucleophilic attack at the β-position by DABCO as the Lewis base catalyst, resulting in an augmented nucleophilic character towards the reaction with aldehydes.

Bimetallic Radical Redox-Relay Catalysis for the Isomerization of Epoxides to Allylic Alcohols

2019 ◽  
Author(s):  
Ke-Yin Ye ◽  
Terry McCallum ◽  
Song Lin
Keyword(s):  
Ring Opening ◽  
High Reactivity ◽  
Hydrogen Atom Transfer ◽  
Organic Radicals ◽  
Epoxide Ring ◽  
Allylic Alcohols ◽  
Epoxide Ring Opening ◽  
Bond Forming ◽  
Co Catalysts ◽  
The Rich

Organic radicals are generally short-lived intermediates with exceptionally high reactivity. Strategically, achieving synthetically useful transformations mediated by organic radicals requires both efficient initiation and selective termination events. Here, we report a new catalytic strategy, namely bimetallic radical redox-relay, in the regio- and stereoselective rearrangement of epoxides to allylic alcohols. This approach exploits the rich redox chemistry of Ti and Co complexes and merges reductive epoxide ring opening (initiation) with hydrogen atom transfer (termination). Critically, upon effecting key bond-forming and -breaking events, Ti and Co catalysts undergo proton-transfer/electron-transfer with one another to achieve turnover, thus constituting a truly synergistic dual catalytic system.<br>

[6 + 3] Annulations of Morita–Baylis–Hillman Carbonates and Dicyanoheptafulvene

2021 ◽  
Author(s):  
Yang Song ◽  
Ruo-Ling Jia ◽  
Shi Deng ◽  
Long-Wei Yang ◽  
Qing-Ling Liu
Keyword(s):  
Lewis Base ◽  
Base Catalyst

An [6 + 3] annulation reaction of Morita-Baylis-Hillman carbonates and dicyanoheptafulvene is accomplished by employing commercially available triphenylphosphine as the Lewis base catalyst. A spectrum of densely functionalized bicyclo[4.3.1]decane architectures...

Synthesis of hydrosilanes via Lewis-base-catalysed reduction of alkoxy silanes with NaBH4

2019 ◽  
Vol 55 (42) ◽  
pp. 5859-5862 ◽  
Author(s):  
Keiya Aoyagi ◽  
Yu Ohmori ◽  
Koya Inomata ◽  
Kazuhiro Matsumoto ◽  
Shigeru Shimada ◽  
...  
Keyword(s):  
Lewis Base ◽  
Base Catalyst ◽  
Hexamethylphosphoric Triamide

Hydrosilanes were synthesized by reduction of alkoxysilanes with BH3 in the presence of hexamethylphosphoric triamide (HMPA) as a Lewis-base catalyst. The reaction was also achieved using an inexpensive and easy-to-handle handled hydride source NaBH4, which reacted with EtBr as a sacrificial reagent to form BH3in situ.

Visible Light-Driven Biginelli Reaction over Mesoporous g-C3 N4 Lewis-Base Catalyst

2018 ◽  
Vol 3 (14) ◽  
pp. 4009-4014 ◽  
Author(s):  
Vidyasagar Devthade ◽  
Gopichand Kamble ◽  
Sachin G Ghugal ◽  
Kishor H. Chikhalia ◽  
Suresh S Umare
Keyword(s):  
Visible Light ◽  
Biginelli Reaction ◽  
Lewis Base ◽  
Base Catalyst ◽  
Visible Light Driven

Mechanisms of Nucleophilic Attack at Carbon - Nitrogen Double Bonds: Reactions of Benzohydrazonoyl Halides with Secondary Amines in Benzene

1997 ◽  
Vol 50 (8) ◽  
pp. 849 ◽  
Author(s):  
Jeffrey E. Rowe ◽  
Kam Lee
Keyword(s):  
Second Order ◽  
Secondary Amines ◽  
Nucleophilic Attack ◽  
Rate Equations ◽  
Rate Data ◽  
Double Bonds ◽  
Effect Data ◽  
First Order ◽  
Amine Molecule

The reactions of a series of substituted benzohydrazonoyl halides with cyclic secondary amines in benzene as solvent are investigated. The rate equations for these reactions were complex and the derived rate data are reported. The element effect data showed that the fluoro compounds only reacted when a second amine molecule was available to assist the reaction, whereas the chloro and bromo compounds reacted by reactions which were both first order and second order in amine (k′′Br : k′′Cl = 9·5 : 1 and k′′′Br :k′′′Cl : k′′′F = 4·7 : 1 : 0·65). The mechanism of these reactions is discussed.

A Polymer-Supported Phosphoramide as a Lewis-Base Catalyst for the Catalytic Aldol Reaction.

ChemInform ◽  
2004 ◽  
Vol 35 (44) ◽  
Author(s):  
Robert A. II Flowers ◽  
Xin Xu ◽  
Cody Timmons ◽  
Guigen Li
Keyword(s):  
Aldol Reaction ◽  
Lewis Base ◽  
Base Catalyst ◽  
Polymer Supported
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