scholarly journals Direct C(sp2)–H alkylation of unactivated arenes enabled by photoinduced Pd catalysis

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Daeun Kim ◽  
Geun Seok Lee ◽  
Dongwook Kim ◽  
Soon Hyeok Hong
Keyword(s):  
Functional Group ◽  
Alkyl Halide ◽  
Alkyl Halides ◽  
Biologically Active ◽  
One Pot ◽  
Bond Forming ◽  
Alkyl Groups ◽  
Alkyl Bromides ◽  
Reaction Proceeds ◽  
Alkylation Reactions

AbstractDespite the fundamental importance of efficient and selective synthesis of widely useful alkylarenes, the direct catalytic C(sp2)–H alkylation of unactivated arenes with a readily available alkyl halide remains elusive. Here, we report the catalytic C(sp2)–H alkylation reactions of unactivated arenes with alkyl bromides via visible-light induced Pd catalysis. The reaction proceeds smoothly under mild conditions without any skeletal rearrangement of the alkyl groups. The direct syntheses of structurally diverse linear and branched alkylarenes, including the late-stage phenylation of biologically active molecules and an orthogonal one-pot sequential Pd-catalyzed C–C bond-forming reaction, are achieved with exclusive chemoselectivity and exceptional functional group tolerance. Comprehensive mechanistic investigations through a combination of experimental and computational methods reveal a distinguishable Pd(0)/Pd(I) redox catalytic cycle and the origin of the counter-intuitive reactivity differences among alkyl halides.

ChemInform Abstract: Indium(III)-Catalyzed Reductive Bromination and Iodination of Carboxylic Acids to Alkyl Bromides and Iodides: Scope, Mechanism, and One-Pot Transformation to Alkyl Halides and Amine Derivatives.

ChemInform ◽  
2014 ◽  
Vol 45 (15) ◽  
pp. no-no
Author(s):  
Toshimitsu Moriya ◽  
Shinichiro Yoneda ◽  
Keita Kawana ◽  
Reiko Ikeda ◽  
Takeo Konakahara ◽  
...  
Keyword(s):  
Carboxylic Acids ◽  
Alkyl Halides ◽  
One Pot ◽  
Alkyl Bromides

Highly Selective One-Pot Synthesis of Polysubstituted Isoflavanes using Styryl Ethers and Electron-Withdrawing ortho-Quinone Methides Generated In Situ

Synlett ◽  
2018 ◽  
Vol 30 (02) ◽  
pp. 189-192 ◽  
Author(s):  
Yujiro Hoshino ◽  
Kiyoshi Honda ◽  
Kenta Tanaka ◽  
Mami Kishimoto ◽  
Naoya Ohtsuka ◽  
...  
Keyword(s):  
Biologically Active ◽  
Quinone Methides ◽  
One Pot ◽  
One Pot Synthesis ◽  
Reaction Proceeds ◽  
Acidic Conditions ◽  
High Yields

A highly selective one-pot synthesis of polysubstituted isoflavanes has been developed. The reaction proceeds through the cycloaddition of methyl styryl ethers, derived from phenylacetaldehyde dimethyl acetals under acidic conditions, with electron-withdrawing ortho-quinone methides generated in situ. When phenylacetaldehyde dimethyl acetals were reacted with salicylaldehydes, the reaction proceeded smoothly to afford the corresponding isoflavanes stereoselectively in high yields and with excellent regioselectivities. The present reaction provides versatile access to functionalized isoflavanes, and constitutes a useful tool for the synthesis of biologically active molecules.

scholarly journals Palladium-catalyzed Heck-type reaction of secondary trifluoromethylated alkyl bromides

2017 ◽  
Vol 13 ◽  
pp. 2610-2616 ◽  
Author(s):  
Tao Fan ◽  
Wei-Dong Meng ◽  
Xingang Zhang
Keyword(s):  
Alkyl Radical ◽  
Functional Group ◽  
High Efficiency ◽  
Mechanistic Studies ◽  
Reaction Conditions ◽  
Type Reaction ◽  
Alkyl Bromides ◽  
Reaction Proceeds ◽  
Palladium Catalyzed ◽  
Hydroxy Groups

An efficient palladium-catalyzed Heck-type reaction of secondary trifluoromethylated alkyl bromides has been developed. The reaction proceeds under mild reaction conditions with high efficiency and excellent functional group tolerance, even towards formyl and hydroxy groups. Preliminary mechanistic studies reveal that a secondary trifluoromethylated alkyl radical is involved in the reaction.

scholarly journals Enantioselective Access to Dialkyl Amines and Alcohols via Ni-Catalyzed Reductive Hydroalkylations

2021 ◽  
Author(s):  
Shan Wang ◽  
Tian-Yi Zhang ◽  
Jian-Xin Zhang ◽  
Huan Meng ◽  
Bi-Hong Chen ◽  
...  
Keyword(s):  
Natural Products ◽  
Functional Group ◽  
Alkyl Halides ◽  
Aliphatic Amines ◽  
Fine Chemicals ◽  
Alkyl Groups ◽  
Simple Protocol ◽  
Enol Esters

Abstract Chiral dialkyl amines and alcohols are ubiquitous in pharmaceuticals, pesticides, natural products and fine chemicals, yet difficult to access due to the challenge to differentiate between the spatially and electronically similar alkyl groups. Herein, we report a nickel-catalyzed enantioselective reductive hydroalkylation of acyl enamines and enol esters with alkyl halides to afford enantioenriched α-branched aliphatic amines and alcohols in good yields with excellent levels of enantioselectivity. The operationally simple protocol provides a straightforward access to chiral dialkyl amine and alcohol derivatives from simple starting materials with great functional group tolerance.

Additive- and Oxidant-Free Expedient Synthesis of Benzimidazoles Catalyzed by Cobalt Nanocomposites on N-Doped Carbon

Synlett ◽  
2019 ◽  
Vol 30 (03) ◽  
pp. 319-324 ◽  
Author(s):  
Zhaozhan Wang ◽  
Tao Song ◽  
Yong Yang
Keyword(s):  
Functional Group ◽  
Direct Synthesis ◽  
Biologically Active ◽  
One Pot ◽  
Mild Conditions ◽  
Wide Range ◽  
High Yields

A one-pot direct synthesis of a wide range of biologically active benzimidazoles through coupling of phenylenediamines and aldehydes catalyzed by a highly recyclable nonnoble cobalt nanocomposite was developed. A broad set of benzimidazoles can be efficiently synthesized in high yields and with good functional-group tolerance under additive- and oxidant-free mild conditions. The catalyst can be easily recycled for successive uses, and the process permits gram-scale syntheses of benzimidazoles.

Regio- and Stereoselective (SN2) N-, O-, C- and S-Alkylation using Trialkyl Phosphates

Synthesis ◽  
2021 ◽  
Author(s):  
Amit banerjee ◽  
Tomohiro Hattori ◽  
Hisashi Yamamoto
Keyword(s):  
Room Temperature ◽  
Alkylating Agents ◽  
Alkyl Halides ◽  
Back Side ◽  
Alkyl Groups ◽  
Wide Range ◽  
Leaving Group ◽  
Reaction Proceeds ◽  
Trialkyl Phosphates ◽  
Trialkyl Phosphate

Bimolecular nucleophilic substitution (S N 2) is one of the most known fundamental reactions in organic chemistry to generate new molecules from two molecules. In principle, a nucleophile attacks from the back side of an alkylating agent having a suitable leaving group, most commonly using a halide. However, alkyl halides are expensive, very harmful, toxic and not so stable which makes them problematic for laboratory use. In contrast, trialkyl phosphates are cheap, readily accessible, stable at room temperature, under air, and are easy to handle but rarely used as alkylating agents in organic synthesis. Here, we describe a mild, straightforward and powerful method for nucleophilic alkylation of various nucleophiles such as N-, O-, C- and S- using readily available trialkyl phosphate. The reaction proceeds smoothly with excellent yield and quantitative yield in many cases and covers a wide range of substrates. Further, the rare stereoselective transfer of secondary alkyl groups has been achieved with inversion of configuration of chiral centers (up to >99% ee).

Elimination reactions – Calculation of rate constants from equilibrium constants and distortion energies by means of no barrier theory

2005 ◽  
Vol 83 (9) ◽  
pp. 1654-1666 ◽  
Author(s):  
J Peter Guthrie ◽  
Leonardo Leandro ◽  
Vladimir Pitchko
Keyword(s):  
Free Energy ◽  
Alkyl Halide ◽  
Equilibrium Constants ◽  
Free Energy Of Activation ◽  
Carbon Carbon Bond ◽  
Alkyl Bromides ◽  
Encounter Complex ◽  
Leaving Group ◽  
Reaction Proceeds ◽  
Rms Error

No barrier theory has been applied to the E2 reactions of five alkyl bromides with ethanolic ethoxide. The model used for these reactions is that the reaction proceeds from the encounter complex of base and alkyl halide to the product encounter complex of halide ion and alkene (and alcohol), and requires five simple processes, which combine to give the concerted elimination: transfer of a proton from carbon to base; a change in geometry at the carbon which loses a proton from sp3 to sp2; breaking the C-leaving group bond; a change in geometry at the carbon which loses the leaving group from sp3 to sp2; and a change in the length of the carbon–carbon bond. The free energy of activation can be calculated with an rms error of 2.58 kcal mol–1 (1 cal = 4.184 J).Key words: Elimination, no barrier theory, rate constant, equilibrium constant.

scholarly journals Enantioselective Access to Dialkyl Amines and Alcohols via Ni-Catalyzed Reductive Hydroalkylations

2020 ◽  
Author(s):  
Shan Wang ◽  
Tian-Yi Zhang ◽  
Jian-Xin Zhang ◽  
Huan Meng ◽  
Bi-Hong Chen
Keyword(s):  
Natural Products ◽  
Functional Group ◽  
Alkyl Halides ◽  
Aliphatic Amines ◽  
Fine Chemicals ◽  
Alkyl Groups ◽  
Simple Protocol

Chiral dialkyl amines and alcohols are ubiquitous in pharmaceuticals, pesticides, natural products and fine chemicals, yet difficult to access due to the challenge to differentiate between the spatially and electronically similar alkyl groups. Herein, we report a nickel-catalyzed enantioselective reductive hydroalkylation of enamides and enolates with alkyl halides to afford enantioenriched α-branched aliphatic amines and alcohols in good yields with excellent levels of enantioselectivity. The operationally simple protocol provides a straightforward access to chiral dialkyl amine and alcohol derivatives from simple starting materials with great functional group tolerance.

Indium(III)-Catalyzed Reductive Bromination and Iodination of Carboxylic Acids to Alkyl Bromides and Iodides: Scope, Mechanism, and One-Pot Transformation to Alkyl Halides and Amine Derivatives

2013 ◽  
Vol 78 (21) ◽  
pp. 10642-10650 ◽  
Author(s):  
Toshimitsu Moriya ◽  
Shinichiro Yoneda ◽  
Keita Kawana ◽  
Reiko Ikeda ◽  
Takeo Konakahara ◽  
...  
Keyword(s):  
Carboxylic Acids ◽  
Alkyl Halides ◽  
One Pot ◽  
Alkyl Bromides
Sign in / Sign up

Export Citation Format

Share Document