Efficient three-component one-pot benzylation and allylation of aldehydes and amines for synthesis of homobenzylamines and homoallylamines

A highly efficient, three-component one-pot benzylation and allylation of aromatic and aliphatic aldehydes and amines affords the corresponding homobenzylamines and homoallylamines in good to excellent yield. The procedure is lauded by its simplicity and manipulability.     

Solvent-free allylation and benzylation of aldimines mediated by zinc powder

A rapid and efficient procedure for allylation and benzylation of aldimines mediated by zinc powder under solvent-free conditions is described. The procedure is operationally simple, higher regioselective, and gives good to excellent yields.     

PdCl2-catalyzed efficient allylation and benzylation of heteroarenes under ligand, base/acid, and additive-free conditions

We present a PdCl(2)-catalyzed protocol for highly efficient allylation and benzylation of a rich variety of N-, O-, and S-containing heteroarenes under base/acid, additive, and ligand-free conditions. The method represents the very few examples for simple, universally applicable, clean, and atom-efficient functionalization of heteroarenes.     

Copper-catalyzed direct benzylation or allylation of 1,3-azoles with N-tosylhydrazones

Cu-catalyzed cross-coupling of N-tosylhydrazones with 1,3-azoles leads to the direct C-H benzylation or allylation. Cu carbene migratory insertion is proposed to play the key role in this transformation.     

Asymmetric alkylation of diarylmethane derivatives. Improved results using methoxyethoxy substituent

Alkylation of 2-methoxyethoxyphenyl phenyl methane using sec-BuLi and (−)-sparteine has been carried out in excellent yields and up to 94% ee. The best results were obtained in allylation reactions but methylation, ethylation, benzylation and trimethylsilylation have all been carried out with acceptable ee.     

Benzylation and Allylation of Naphthols Using Amberlyst-15

A simple and efficient method has been developed for benzylation and allylation of naphthols by treatment of the compounds with benzylic and allylic alcohols, respectively, in the presence of amberlyst-15. Several heterogeneous catalysts were screened for the reaction, and amberlyst-15 was found to be most effective.     

Aqueous single step synthesis and structural characterization of allylated,propargylated, and benzylated 3-substituted 3-aminooxindoles

Efficient zinc-mediated allylation, propargylation, and benzylation of isatin-derived imines were undertaken for the synthesis of 3-substituted 3-aminooxindoles with ≈80% yield. Such alternative approach has efficiently avoided the use of catalysts, severe reaction conditions, multistep procedures, and reaction additives. For exploring and materializing the synthetic utility, different allyl, propargyl, and benzyl bromides were used for generalizing the synthetic route. The structure of the synthesized compounds was established and confirmed by ¹H NMR, ¹³C NMR, FTIR, and mass spectroscopic techniques.     

First Magnesium-mediated Carbonyl Benzylation in Water

Catalyzed by AgNO3, Mg was found for the first time to be able to mediate the coupling reaction between aromatic aldehydes and benzyl bromide or chloride in water. The yields were slightly higher than the recent results for Mg-mediated allylation despite the fact that aqueous benzylation is intrinsically much harder than allylation. It was also found that the coupling reaction was chemoselective for aromatic aldehydes over aliphatic aldehydes, and chemoselective for aromatic aldehydes over aromatic ketones.     

Trialkylsilyl triflimides as easily tunable organocatalysts for allylation and benzylation of silyl carbon nucleophiles with non-genotoxic reagents

Trialkylsilyl triflimides generated in situ are unique catalysts for the electrophilic benzylation or allylation of trialkylsilylenol ethers or allyl trialkylsilanes with non-genotoxic alkylating reagents such as benzyl and allyl acetates. In most cases the reactions are fast at room temperature and yields are high. The reaction works particularly well with electron-rich benzyl donors including derivatives of pyrrole, indole and furane.     

Di-μ-hydroxy-bis(N,N,N′,N′-tetramethylenediamine)-copper(II) chloride [Cu(OH)·TMEDA]2Cl2: an efficient, practical catalyst for benzylation and allylation of amides

An efficient protocol for the benzylation or allylation of amides using the corresponding benzyl or allyl chlorides as electrophiles under basic conditions with commercially available 5 mol % of [Cu(OH)TMEDA]₂Cl₂ as catalyst was developed. Under these conditions, unprotected amino acids were benzylated without any racemization.     

Silver‐Catalyzed Benzylation and Allylation of Tertiary Alkyl Bromides with Organozinc Reagents

Silver salts catalyze the benzylation and allylation of tertiary alkyl bromides with organozinc reagents. The reactions create quaternary carbon centers efficiently. Treatment of gem‐dibromoalkanes with benzylic or allylic zinc reagents under silver catalysis leads to dibenzylation or diallylation. The functional‐group compatibility of the present reactions is wider than that of the previous reactions with Grignard reagents.     

An efficient Yb(OTf)3 catalyzed alkylation of 1,3-dicarbonyl compounds using alcohols as substrates

A highly efficient and environmentally friendly method for catalytic benzylation/allylation of 1,3-dicarbonyl compounds with alcohols has been developed by using Yb(OTf)₃ as a catalyst. The reactions proceed smoothly to give the desired products in moderate to excellent yields, mostly at room temperature. The catalyst can be recovered and reused at least six times without visible loss of catalytic activity for such reactions.     

钐试剂在合成中的应用I. 金属钐作用下烯丙基和苄基卤代物与羰基化合物的反应

本文研究了金属钐作用下的Barbier型反应。结果表明, 经氯化汞活化的金属钐对酮类化合物与烯丙基或苄基卤代物的反应很有效, 可高产率地生成叔醇。此反应有很好的区位选择性和化学选择性, 与α, β-不饱和酮的反应未发现1, 4-加成产物生成, 与环上有卤素(Br, Cl)取代的芳香酮反应, 取代基不受影响。产物的形成可能通过了有机钐中间体。     

Organophotoredox/palladium dual catalytic decarboxylative Csp3–Csp3 coupling of carboxylic acids and π-electrophiles

A dual catalytic decarboxylative allylation and benzylation method for the construction of new C(sp³)–C(sp³) bonds between readily available carboxylic acids and functionally diverse carbonate electrophiles has been developed. The new process is mild, operationally simple, and has greatly improved upon the efficiency and generality of previous methodology. In addition, new insights into the reaction mechanism have been realized and provide further understanding of the harnessed reactivity.

A dual catalytic decarboxylative allylation and benzylation method for the construction of new C(sp³)–C(sp³) bonds between readily available carboxylic acids and functionally diverse carbonate electrophiles has been developed.     

杂环化合物的烯丙基化和苄基化反应的研究概况

分子中含O、S和N的杂环化合物,如呋喃、噻吩、吡咯和吲哚等及其衍生物是许多天然产物的活性成分,也是功能材料的重要构件。 因此,开展杂环化合物简便高效的官能化反应的研究显得尤为重要。 其中杂环化合物的烯丙基与苄基化反应是最具有吸引力的杂环官能团化反应之一。 本文综述了杂环化合物的烯丙基化和苄基化反应的研究进展。     

Yb(OTf)3-promoted effective benzylation and allylation with N-tosyl amino group as a stable leaving group

A simple, inexpensive, environmentally friendly, and highly efficient benzylation and allylation of 1,3-dicarbonyl compounds with sulfonamides in the presence of Yb(OTf)₃ is described. Yb(OTf)₃ was proved to be a good catalyst for the cleavage of sp³ carbon–nitrogen bond. Various 1,3-dicarbonyl compounds can couple with a broad range of tosyl-activated benzylic and allylic amines to give diversely functionalized products in good to excellent yields.     

Efficient and selective alkylation of arenes and heteroarenes with benzyl and allyl ethers using a Ir/Sn bimetallic catalyst

A high-valent heterobimetallic catalyst namely [Ir₂(COD)₂(SnCl₃)₂(Cl)₂(μ-Cl)₂] (5 mol %), or dual catalyst system of [Ir(COD)Cl]₂ (1 mol %) and SnCl₄ (4 mol %), promotes the benzylation or allylation of arenes and heteroarenes using ethers as the alkylating agents. An electrophilic mechanism is proposed from a Hammett correlation.     

Metal triflate-catalyzed cationic benzylation and allylation of 1,3-dicarbonyl compounds

The rare earth metal and hafnium triflate-catalyzed secondary benzylation and allylation of 1,3-diketones, ketoesters, and ketoamides are described. The procedure was carried out under non-anhydrous conditions. Various 1-phenylethyl cations were generated from substituted 1-phenylethanols using 0.5 mol % of the metal triflates in CH3NO2. The cations reacted with 1,3-diketones and ketoesters to give benzylated products in high yields. Following the GC analysis, the reaction conditions were easily optimized by the selection of catalysts based on the Lewis acidity of the triflates and reaction temperature. A tertiary-alkylated diketone and a corresponding ketoester were also benzylated to afford products with a quaternary carbon atom in 57-84% yield. The ketoamide reactions required stronger Lewis acids than those used in the diketone and ketoester reactions. The reactions of benzylic alcohols possessing various substituents on the aromatic ring and dibenzoylmethane (2b) as a diketone were examined in the presence of Hf(OTf)4. Electron-rich benzylic alcohols reacted with 2b in 86-96% yield, and electron-deficient alcohol gave the desired product in 79-65% yield. Despite possessing a strong electron-withdrawing group, the reaction of 1-(4-nitrophenyl)ethanol gave the corresponding product in 61% yield. It was also possible to use allylic alcohols directly for the allylation of diketone 2b. The catalyst can be recovered by water extraction and reused up to five times.     

Expedient Iron‐Catalyzed C−H Allylation/Alkylation by Triazole Assistance with Ample Scope

Triazole assistance set the stage for a unified strategy for the iron‐catalyzed C?H allylation of arenes, heteroarenes, and alkenes with ample scope. The versatile catalyst also proved competent for site‐selective methylation, benzylation, and alkylation with challenging primary and secondary halides. Triazole‐assisted C?H activation proceeded chemo‐, site‐, and diastereo‐selectively, and the modular TAM directing group was readily removed in a traceless fashion under exceedingly mild reaction conditions.     

Brönsted acid ionic liquid-catalyzed direct benzylation, allylation and propargylation of 1,3-dicarbonyl compounds with alcohols as well as one-pot synthesis of 4H-chromenes

Recyclable ionic Brönsted acid was prepared in nearly quantitative yield by reacting 1-butylimidazole with an equimolar amount of 1,3-propanesultone, followed by treatment with an equimolar amount of trifluoromethanesulfonic acid. The ionic Brönsted acid-catalyzed direct benzylation, allylation and propargylation of 1,3-dicarbonyl compounds with various alcohols in ionic liquid [N-ethyl-N-methyl imidazolium trifluoromethanesulfonate (EMIOTf)], at 100 °C for 3 h proceeded smoothly to give the corresponding products in good to excellent yields without the use of any hazardous or volatile solvents and without any by-product such as salts. Furthermore, tandem benzylation-cyclization-dehydration of 1,3-dicarbonyl compounds to give functionalized 4H-chromenes was also achieved in this catalytic reaction.