Mechanism of SN2 Alkylation Reactions of Lithium Organocuprate Clusters with Alkyl Halides and Epoxides. Solvent Effects, BF3Effects, and Trans-Diaxial Epoxide Opening

2000 ◽  
Vol 122 (30) ◽  
pp. 7294-7307 ◽  
Author(s):  
Seiji Mori ◽  
Eiichi Nakamura ◽  
Keiji Morokuma
Keyword(s):  
Solvent Effects ◽  
Alkyl Halides ◽  
Epoxide Opening ◽  
Alkylation Reactions

scholarly journals Kinetic solvent effects in the reduction of alkyl halides by {Sm[N(SiMe3)2]2(THF)2}

2018 ◽  
Vol 857 ◽  
pp. 52-57 ◽  
Author(s):  
Tesia V. Chciuk ◽  
Sandeepan Maity ◽  
Robert A. Flowers
Keyword(s):  
Solvent Effects ◽  
Alkyl Halides

Ephedrines as Chiral Auxiliaries in Enantioselective Alkylation Reactions of Acyl Ephedrine Amides and Esters: A Review

2018 ◽  
Vol 15 (1) ◽  
pp. 38-83 ◽  
Author(s):  
Alejandro Cruz ◽  
Itzia I. Padilla-Martínez ◽  
Maria E. Bautista-Ramirez
Keyword(s):  
Asymmetric Synthesis ◽  
Bond Formation ◽  
Alkyl Halides ◽  
Aldol Reactions ◽  
Alkylation Reaction ◽  
Chiral Auxiliaries ◽  
Asymmetric Alkylation ◽  
Chiral Compounds ◽  
High Yields ◽  
Alkylation Reactions

Background: In modern chemistry, the asymmetric synthesis for the preparation of high purity chiral compounds to be used as pharmaceuticals or additives in foods have been of capital importance. Chiral auxiliary reagents are used to control the stereochemistry of the reaction in the generation of new chiral compounds, in this context, Ephedra compounds (ephedrines and pseudoephedrines) and some of their derivatives have been broadly used as chiral ligands in catalysis or chiral inductors in asymmetric synthesis. Objective: This review focuses on recent progress in the use of ephedra compounds and their N-substituted derivatives as chiral auxiliaries in the area of asymmetric synthesis, via the alkylation reaction of the enolates derived from their corresponding N-Acyl or O-Acyl derivatives, in the C-C bond formation. Conclusion: A vast amount of work has been done about the use of ephedra compounds in asymmetric synthesis area, in general, it was found that pseudoephedrines are much more effective than ephedrines and are preferred as chiral auxiliaries in the asymmetric alkylation of the corresponding N-acyl amides or O-Acyl esters. Alkylation with alkyl halides requires the use of more than 4 equivalents of LiCl to accelerate the alkylation rate and to complete the reaction without effecting the diastereoselectivity of the process. In contrast, the use of secondary alkyl halides was found to make the reaction very slow. Furthermore, a lot of work about the alkylation reaction in the opening of epoxides and aziridines, aldolic condensation, Manich reaction, addition of nucleophiles to α,β-unsaturated ephedrine amides and Michael additions have been demonstrated to be effective in the C-C bond formation. The aldol reaction of chiral enolates, proceeds with decreasing yields and enantioselectivities as the steric demand of the α-R of ephedrine amides and the size of carbonyl compound increase. In addition, the use of branched groups on N,N-disubstituted norephedrine esters is highly recommended in the aldol reactions of aromatic and aliphatic aldehydes.In the case of N-Acyl or O-Acyl ephedrines supported on polymers, the reaction proceed with good enantioselectivities but low yields, the enantioselectivities are goods but the yields are low. In general, the removal step of the auxiliary proceeds with low to high yields but without epimerization.

Synthesis of α-Alkylated Ketones via Selective Epoxide Opening/Alkylation Reactions with Primary Alcohols

2021 ◽  
Author(s):  
Sertaç Genç ◽  
Süleyman Gülcemal ◽  
Salih Günnaz ◽  
Bekir Çetinkaya ◽  
Derya Gülcemal
Keyword(s):  
Primary Alcohols ◽  
Epoxide Opening ◽  
Alkylation Reactions

Kinetics of quaternization reactions of polymeric amines

1989 ◽  
Vol 54 (3) ◽  
pp. 663-672
Author(s):  
Martin Přádný ◽  
Stanislav Ševčík ◽  
Stela Dragan
Keyword(s):  
Alkylating Agent ◽  
Alkyl Halides ◽  
Differential Rate ◽  
Hydroxyethyl Methacrylate ◽  
Ethyl Methacrylate ◽  
Slowing Down ◽  
Conformational Effects ◽  
Alkylation Reactions ◽  
Kinetics Of ◽  
Steric Hindrances

The paper deals with kinetics phenomena occurring in the quaternization of some polymeric amines, such as poly[2-(dimethylamino)ethyl methacrylate], poly{N-[3-(dimethylamino)propyl]-acrylamide}, and poly[2-(dimethylamino)ethyl methacrylate-co-2-hydroxyethyl methacrylate], with alkyl halides. The accelerating and slowing-down effects which take place in the alkylation reactions are discussed on the basis of the reaction course, i.e. of the dependence of differential rate constants on the conversion fraction of the reaction. Accelaration of the reaction is affected by the increasing polarity of microsurroundings of the reacting groups, while electrostatic and steric hindrances of the reacted groups slow down the reaction. Conformational effects, chemical and solvation interactions in the polymer-solvent-alkylating agent system and tacticity of the polymer are also operative.

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.

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