Showing papers on "Alkylation published in 2011"
TL;DR: In this article, the synthesis of amines by the amination of alcohols, by means of the so-called borrowing hydrogen methodology, is presented Compared to other synthetic methodologies for the synthesis, these transformations are highly attractive because often alcohols are readily available starting materials, some of them on a large scale from renewable sources.
Abstract: In this Minireview, the synthesis of amines by the amination of alcohols, by means of the so-called borrowing hydrogen methodology, is presented Compared to other synthetic methodologies for the synthesis of amines, these transformations are highly attractive because often alcohols are readily available starting materials, some of them on a large scale from renewable sources In addition, the amination of alcohols produces water as the only by-product, which makes the process potentially environmentally benign Already today, lower alkyl amines are produced in bulk by the chemical industry with this synthetic method In particular, the recent progress applying organometallic catalysts based on iridium, ruthenium, and other metals will be discussed Notable recent achievements include the conversion of challenging substrates such as diols, the development of recyclable catalysts, milder reaction temperatures, and the direct alkylation of ammonia or its equivalents with alcohols
597 citations
TL;DR: A mild, operationally simple, room temperature method for the α-trifluoromethylation of enolsilanes, achieved through application of the recently described photoredox catalysis strategy, and a new activation mode for the direct enantioselective alkylation of aldehydes.
Abstract: The unique physical and chemical advantages conferred by the C–F bond have led to the broad exploitation of this motif throughout the pharmaceutical,[1] materials,[2] and agrochemical[3] sectors. In drug design, for instance, incorporation of polyfluorinated alkyl groups, such as CF3 moieties, can profoundly impact the activity, metabolic stability, lipophilicity, and bioavailability of lead compounds.[1,4] Not surprisingly, the development of methods for the production of carbonyl-based synthons bearing α-CF3 substitution has emerged as a central objective in the field of chemical synthesis. Although important recent advances have been made toward this goal, there are currently few operationally simple methods for the conversion of enolates (or enolate equivalents) to α-trifluoromethylated carbonyl motifs. Standard alkylation methods are generally not productive, due to the negative polarization of the trifluoromethyl moiety, thus specially tailored reagents have been developed to furnish an electrophilic CF3 equivalent.[5] Alternatively, in recent years, a set of radical (Et3B/O2) and organometallic (Rh-catalyzed) approaches have been pursued to introduce the trifluoromethyl species through enolate derivatives.[6,7] While these methods offer significant progress toward solving the “α-CF3 carbonyl problem”, issues of substrate scope, cryogenic temperatures, and regioselectivity of CF3 incorporation remain prominent concerns. Herein, we describe a mild, operationally simple, room temperature method for the α-trifluoromethylation of enolsilanes, achieved through application of our recently described photoredox catalysis strategy.[8,9] Furthermore, a one-pot protocol has been developed to enable the rapid fluoroalkylation of ketones, esters, and amides, without the isolation of pre-generated enolsilane intermediates.
Design plan: Recently, our laboratory established a new activation mode for the direct enantioselective alkylation of aldehydes. Termed photoredox organocatalysis, this novel strategy exploits a synergistic relationship between chiral amine and organometallic photoredox catalysts as a means to access electrophilic alkyl radicals that rapidly combine with enamines under ambient conditions.[8] We postulated that the mechanistic logic underlying photoredox catalysis could be extended to devise a simple yet general approach to the α-
trifluoromethylation of a range of enolates or enolate equivalents [Eq. (1)]. In this context, we elected to employ enolsilanes and silylketene acetals as suitable enolic substrates, given their synthetic accessibility and well-established capacity to combine with electrophilic coupling partners.[10] As outlined in Scheme 1, we proposed that photoexcitation of [Ru(bpy)3]2+ (1) using a household light bulb, followed by single-electron reduction of 2 should rapidly generate [Ru-(bpy)3]+ (3).[11] As we have previously described, this potent one-electron reductant can readily participate in single-electron transfer (SET) with CF3I to generate the electrophilic trifluoromethyl radical, which we hoped would rapidly combine with enolsilane 4 to furnish α-silyloxy radical 5. The oxidation potential of 5 is anticipated to be sufficiently low to allow for facile oxidation by *[Ru(bpy)3]2+ (2) (E1/2red = 0.79 V vs. SCE in MeCN)[12] to generate silyloxocarbenium 6, an unstable species that should rapidly undergo hydrolysis to yield the desired α-trifluoromethylated carbonyl product.[13]
Scheme 1
Proposed mechanism for carbonyl α-trifluoromethylation.
As shown in Table 1, our initial studies confirmed the feasibility of the proposed trifluoromethylation when the tert-butyldimethylsilyl (TBS) substituted enolsilane 7 was exposed to CF3I, 0.5 mol% [Ru(bpy)3Cl2] (1), and a 26 W household fluorescent lamp in the presence of 1.5 equivalents of Et3N in DMF (entry 1, 35% yield). Importantly, no alkylation was observed when either amine base, [Ru(bpy)3Cl2] catalyst, or light was excluded from this protocol (entries 2–4). Early investigations further revealed the importance of employing a tertiary amine base to serve both as a sacrificial reductant and to scavenge the deleterious HI byproduct.[11,14,15] With this in mind, the reaction efficiency was further enhanced by 1) the use of a more reducing and more basic amine base, iPr2NEt, 2) incorporation of a less acid-labile silyl group (TIPS) on the enolsilane substrate, and 3) the addition of water to aid in the capture of the putative silyl cation intermediate (entries 5–8, 45–94% yield). Indeed, the observed levels of reaction efficiency using 0.5 mol% [Ru(bpy)3Cl2] (1) with triisopropylsilyl-substituted enolsilane 7 in the presence of THF-H2O and iPr2NEt, established these conditions as optimal for further exploration.
Table 1
Trifluoromethylation of enolsilanes: initial studies.
As revealed in Table 2, a broad range of ketone-derived enolsilanes that exhibit diverse electronic and steric properties readily participate in this new photoredox trifluoromethylation protocol. Specifically, this fluoroalkylation strategy is tolerant to enolsilane coupling partners that incorporate arenes, nitriles, and halogens (entries 1–7, 66–92%), as well as sulfides, ethers, and carbamates (entries 10–13, 59–73%). Moreover, sterically demanding substrates (entry 15, adamantyl, 84%), as well as large ring sizes (entry 14, 68%), are accommodated with minimal impact on yield. Intriguingly, we observe an important structural bifurcation in that TIPS-derived enolsilanes of aromatic ketones (entries 1–7, 66–92% yield) typically achieve higher yields, whereas for aliphatic ketones, TES-substituted enolsilanes provide generically higher yields in this trifluoromethylation protocol (entries 8–15, 59–84% yield). Interestingly, this trend is also maintained in the formation of quaternary carbon centers (entry 16, 76% yield).
Table 2
Trifluoromethylation of enolsilanes: ketone scope.
We next sought to examine the applicability of this trifluoromethylation strategy to other carbonyl classes, specifically silylketene acetal and N,O-acetal substrates derived from ester and amide synthons (Table 3). To our initial surprise, we observed that silylketene acetals of δ-valerolactone underwent rapid alkylation in the presence of the 26 W fluorescent light, without the requirement of the photoredox catalyst [Ru(bpy)3Cl2] (entry 1, 85% yield). In this case we assume that a photon-induced charge-transfer complex mechanism is likely operative.[16] Notably, these photoredox catalyst-free trifluoromethylation conditions can be successfully utilized with a range of silylketene acetals and N,O-acetals, provided monosubstituted enols are employed (entries 2 and 4, 76–86% yield). Indeed, the more sterically demanding disubstituted silylketene acetals were found to be significantly less activated toward α-trifluoromethylation using this alternative light-induced charge-transfer mechanism, providing only moderate alkylation yields after extended reaction times (24 h). Fortunately, high levels of trifluoromethylation efficiency could be re-established for these structurally encumbered substrates using our standard [Ru(bpy)3Cl2]-catalyzed photoredox conditions (entries 3 and 5, 74–84% yield).
Table 3
Trifluoromethylation of enolsilanes: esters and amides.
As a demonstration of the synthetic utility of our catalytic photoredox protocol, we have developed a facile, two-step, one-flask procedure for the direct α-trifluoromethylation of a broad range of carbonyl-containing substrates (Table 4). As shown, the enolsilane is first formed in situ in the presence of photocatalyst 1, silylating agent, and an appropriate base. The resultant enolsilane (without isolation or purification) is then exposed to α-trifluoromethylation conditions to generate the target α-alkylation adduct in a single reaction vessel. This procedure was found to be applicable to ketone, ester, and amide substrates, delivering the desired products with good overall efficiency (entries 1–3, 67–78% yield).
Table 4
Direct, one-pot a-perfluoroalkylation of carbonyl compounds.
Importantly, this one-pot protocol is also amenable to a range of α-fluoroalkylations. When subjected to the outlined procedure, ethyl caprylate underwent perfluoroalkylation (n-propyl and isopropyl) and difluoroalkylation with excellent levels of reaction efficiency (entries 4–6, 75–92% yield).
In summary, we have introduced a new photoredox-based method that allows for facile α-trifluoromethylation of enolsilanes, silylketene acetals and N,O-acetals derived from a broad range of ketone, ester, and amide substrates. Moreover, we have devised a one-pot protocol that enables the rapid and trivial installation of the trifluoromethyl moiety, as well as other fluoroalkyl groups, directly to a wide array of carbonyl systems. We expect this novel protocol to be of broad utility in the synthesis of biologically active organofluorine containing medicinal agents.
389 citations
TL;DR: The palladium-catalyzed direct 2-alkylation reaction of free N-H indoles has been developed and represents the first example for a generally applicable, direct C-H alkylation of indole at the 2-position.
Abstract: A palladium-catalyzed direct 2-alkylation reaction of free N-H indoles has been developed. This reaction relies on a norbornene-mediated cascade C–H activation process at the indole ring, which features high regioselectivity and excellent functional group tolerance. The reaction represents the first example for a generally applicable, direct C–H alkylation of indole at the 2-position.
273 citations
231 citations
TL;DR: A direct alkylation of various heteroaryls using stoichiometric potassium alkyl- and alkoxymethyltrifluoroborates leads to the synthesis of complex substituted heterocycles with yields up to 89%.
223 citations
TL;DR: Coupling of an alkyl chloride with a secondary benzamide derivative at the ortho-position can be achieved in good to excellent yield in the presence of a cobalt catalyst and cyclohexylmagnesium chloride in diethyl ether at room temperature.
Abstract: Coupling of an alkyl chloride with a secondary benzamide derivative at the ortho-position can be achieved in good to excellent yield in the presence of a cobalt catalyst and cyclohexylmagnesium chloride in diethyl ether at room temperature. Cyclohexylmagnesium chloride formally acts to remove hydrogen atoms from the amide nitrogen and from the ortho-position and to generate the active cobalt species.
213 citations
TL;DR: The reaction of primary and secondary amines with benzylic alcohols (II) under thermal conditions provides a synthesis of higher amines as mentioned in this paper, and the reaction is shown to be reversible.
Abstract: The reaction of primary and secondary amines with benzylic alcohols (II) under thermal conditions provides a synthesis of higher amines.
202 citations
TL;DR: Impregnated ruthenium catalyst is a versatile, inexpensive, and simple system for the selective N-monoalkylation of amino derivatives with poor nucleophilic character, such as aromatic and heteroaromatic amines, sulfonamide, sulfinamides, and nitroarenes.
Abstract: Various impregnated metallic salts on magnetite have been prepared, including cobalt, nickel, copper, ruthenium, and palladium salts, as well as a bimetallic palladium–copper derivative. Impregnated ruthenium catalyst is a versatile, inexpensive, and simple system for the selective N-monoalkylation of amino derivatives with poor nucleophilic character, such as aromatic and heteroaromatic amines, sulfonamides, sulfinamides, and nitroarenes, using in all cases alcohols as the initial source of the electrophile, through a hydrogen autotransfer process. In the case of sulfinamides, this is the first time that these amino compounds have been alkylated following this strategy, allowing the use of chiral sulfinamides and secondary alcohols to give the alkylated compound with a diastereomeric ratio of 92:8. In these cases, after alkylation, a simple acid deprotection gave the expected primary amines in good yields. The ruthenium catalyst is quite sensitive, and small modifications of the reaction medium can chang...
200 citations
TL;DR: An efficient and environmentally benign catalytic system for the synthesis of various organic amines catalyzed by the water-soluble and air-stable (pentamethylcyclopentadienyl)-iridium-ammine iodide complex, [Cp * Ir(NH 3 ) 3 ][I] 2 (Cp* = pentamethyl-cyclopentadiyl), has been developed as discussed by the authors.
Abstract: An efficient and environmentally benign catalytic system for the synthesis of various organic amines catalyzed by the water-soluble and air-stable (pentamethylcyclopentadienyl)-iridium-ammine iodide complex, [Cp * Ir(NH 3 ) 3 ][I] 2 (Cp * =pentamethyl-cyclopentadienyl), has been developed. A wide variety of secondary and tertiary amines were synthesized by the N-alkylation reactions of theoretical equivalents of amines with alcohols in water under air without a base. The synthesis of cyclic amines was also achieved by the N-alkylation of benzylamine with diols. Furthermore, the recycle use of the present water-soluble Cp * Ir catalyst was accomplished.
197 citations
179 citations
TL;DR: A metal-free novel, simple, and highly efficient method for the direct C2-alkylation of azoles with alcohols and ethers has been developed on the basis of an oxidative C-H activation process.
TL;DR: A highly efficient and generally applicable method has been developed to functionalize the ortho-C(sp(2))-H bonds of picolinamide (PA)-protected benzylamine substrates with a broad range of β-H-containing alkyl halides.
TL;DR: Experimental observations suggest that these alkylation reactions occur through an unusual inner-sphere mechanism involving binding of the prochiral enolate nucleophile directly to the palladium center.
Abstract: α-Quaternary ketones are accessed through novel enantioselective alkylations of allyl and propargyl electrophiles by unstabilized prochiral enolate nucleophiles in the presence of palladium complexes with various phosphinooxazoline (PHOX) ligands. Excellent yields and high enantiomeric excesses are obtained from three classes of enolate precursor: enol carbonates, enol silanes, and racemic β-ketoesters. Each of these substrate classes functions with nearly identical efficiency in terms of yield and enantioselectivity. Catalyst discovery and development, the optimization of reaction conditions, the exploration of reaction scope, and applications in target-directed synthesis are reported. Experimental observations suggest that these alkylation reactions occur through an unusual inner-sphere mechanism involving binding of the prochiral enolate nucleophile directly to the palladium center.
TL;DR: Chiral 1,2,3-triazoliums have been designed, and the rational structural modification based on their unique anion-binding abilities has led to the establishment of the highly enantioselective alkylation of 3-substituted oxindoles.
Abstract: Chiral 1,2,3-triazoliums have been designed, and the rational structural modification based on their unique anion-binding abilities has led to the establishment of the highly enantioselective alkylation of 3-substituted oxindoles.
TL;DR: The catalytic process shows promise for the efficient and economic synthesis of amine, carboxamide, sulfonamide, and ketone derivatives because of the simplicity of the system and ease of operation.
Abstract: Complicated and expensive organic ligands are normally essential in fine chemical synthesis at prepara- tive or industrial levels. The synthesis of fine chemicals by using heterogene- ous catalyst systems without additive organic ligand is highly desirable but severely limited due to their poor gen- erality and rigorous reaction condi- tions. Here, we show the results of carbon-nitrogen or carbon-carbon bond formation catalyzed by an Ag/Mo hybrid material with specific Ag6Mo10O33 crystal structure. 48 nitro- gen- or oxygen-containing compounds, that is, amines, carboxamides, sulfona- mides, and ketones, were successfully synthesized through a borrowing-hy- drogen mechanism. Up to 99 % isolat- ed yields were obtained under relative- ly mild conditions without additive or- ganic ligand. The catalytic process shows promise for the efficient and economic synthesis of amine, carboxa- mide, sulfonamide, and ketone deriva- tives because of the simplicity of the system and ease of operation.
TL;DR: The proposed mechanism reveals that an alcohol or amine substrate is initially dehydrogenated to an aldehyde/ketone or NH-imine with concomitant formation of a [PtSn] hydride, which forms an N-substituted imine which is then reduced to a new amine product under a nitrogen atmosphere or remains unchanged as the final product under an oxygen atmosphere.
Abstract: Versatile syntheses of secon- dary and tertiary amines by highly effi- cient direct N-alkylation of primary and secondary amines with alcohols or by deaminative self-coupling of pri- mary amines have been successfully re- alized by means of a heterogeneous bi- metallic Pt-Sn/g-Al2O3 catalyst (0.5 wt % Pt, Pt/Sn molar ratio = 1:3) through a borrowing-hydrogen strategy. In the presence of oxygen, imines were also efficiently prepared from the tandem reactions of amines with alco- hols or between two primary amines. The proposed mechanism reveals that an alcohol or amine substrate is initial- ly dehydrogenated to an aldehyde/ ketone or NH-imine with concomitant formation of a (PtSn) hydride. Conden- sation of the aldehyde/ketone species or deamination of the NH-imine inter- mediate with another molecule of amine forms an N-substituted imine which is then reduced to a new amine product by the in-situ generated (PtSn) hydride under a nitrogen atmosphere or remains unchanged as the final product under an oxygen atmosphere. The Pt-Sn/g-Al2O3 catalyst can be easily recycled without Pt metal leach- ing and has exhibited very high catalyt- ic activity toward a wide range of amine and alcohol substrates, which suggests potential for application in the direct production of secondary and ter- tiary amines and N-substituted imines.
TL;DR: In this paper, deep eutectic solvents (DES) and lipase were used for N-alkylation of primary amines, which avoided complexity of multiple alkylations giving products in good yields.
Abstract: Biocatalysts or deep eutectic solvents (DES) are effective for selective N-alkylation of various aromatic primary amines. These methods avoided complexity of multiple alkylations giving products in good yields. Both DES and lipase can be recycled and re-used at least five times. In addition, these catalysts are biodegradable, non-toxic and cost-effective.
TL;DR: A selective C(3)-alkylation via activation/functionalization of sp(3) C-H bond of saturated cyclic amines was promoted by (arene)ruthenium(II) complexes featuring a bidentate phosphino-sulfonate ligand upon reaction with aldehydes.
Abstract: A selective C(3)-alkylation via activation/functionalization of sp(3) C-H bond of saturated cyclic amines was promoted by (arene)ruthenium(II) complexes featuring a bidentate phosphino-sulfonate ligand upon reaction with aldehydes. This highly regioselective sustainable transformation takes place via initial dehydrogenation of cyclic amines and hydrogen autotransfer processes.
TL;DR: In this paper, an asymmetric cross-coupling of an unactivated alkyl electrophile, an aryl metal, a boronate ester, and a secondary (cyclopropyl)-alkyl metal compound was shown to have significant enantioselectivity.
Abstract: With the aid of a chiral nickel catalyst, enantioselective γ- (and δ-) alkylations of carbonyl compounds can be achieved through the coupling of γ-haloamides with alkylboranes. In addition to primary alkyl nucleophiles, for the first time for an asymmetric cross-coupling of an unactivated alkyl electrophile, an arylmetal, a boronate ester, and a secondary (cyclopropyl) alkylmetal compound are shown to couple with significant enantioselectivity. A mechanistic study indicates that cleavage of the carbon–halogen bond of the electrophile is irreversible under the conditions for asymmetric carbon–carbon bond formation.
TL;DR: A selective catalytic alkylation reaction of alkenes with alcohols that forms a carbon-carbon bond between vinyl carbon-hydrogen (C–H) and carbon-Hydroxy centers with the concomitant loss of water is reported.
Abstract: Alkenes and alcohols are among the most abundant and commonly used organic feedstock in industrial processes. We report a selective catalytic alkylation reaction of alkenes with alcohols that forms a carbon-carbon bond between vinyl carbon-hydrogen (C-H) and carbon-hydroxy centers with the concomitant loss of water. The cationic ruthenium complex [(C(6)H(6))(PCy(3))(CO)RuH](+)BF(4)(-) (Cy, cyclohexyl) catalyzes the alkylation in solution within 2 to 8 hours at temperatures ranging from 75° to 110°C and tolerates a broad range of substrate functionality, including amines and carbonyls. Preliminary mechanistic studies are inconsistent with Friedel-Crafts-type electrophilic activation of the alcohols, suggesting instead a vinyl C-H activation pathway with opposite electronic polarization.
TL;DR: In this article, a strategy for design of active catalysts for green chemical and biomass conversion processes is discussed and the important role of solid Lewis acids was suggested in acetylation of alcohols with acetic anhydride by cation-exchanged clay, Friedel-Crafts acylation and alkylation of aromatic compounds with metal salts of heteropolyacids.
Abstract: Design of solid acid catalysts is one of the key technologies to establish environmental friendly catalytic processes. Featuring cation-exchanged clay and metal salts of heteropolyacids as model solid acid catalysts, a strategy for design of active catalysts for green chemical and biomass conversion processes is discussed. The important role of solid Lewis acids was suggested in acetylation of alcohols with acetic anhydride by cation-exchanged clay, Friedel–Crafts acylation and alkylation of aromatic compounds with metal salts of heteropolyacids, and hydrolysis of cellulose into saccharides. The significant influence of reactor design and reaction conditions on dehydration of saccharides into 5-hydroxymethylfurfural (HMF) is also discussed.
TL;DR: In this paper, an iron oxide immobilized palladium catalyst was used for the N-alkylation of amines with alcohols under base and organic ligand free conditions.
TL;DR: A mechanistic study points to competitive ligand binding as the underlying cause for the limited substrate scope observed in the first intermolecular allylic C H alkylation reaction of unactivated a-olefins.
Abstract: A significantly improved method for the intermolecular allylic C—H alkylation of unactivated and activated olefins is presented.
TL;DR: In this article, a study of the reaction using deuterium-labeled reagents was performed, indicating that the dehydrogenation and hydrogenation steps do not take placed on the same copper atom coordination sphere, with the condensation step occurring out of the deuterating catalytic species.
TL;DR: Chiral phosphoric acid-catalysed Friedel-Crafts alkylation reactions of indoles, pyrrole and 3-(dimethylamino)phenol with racemic spiro indolin-3-ones have been realised.
Abstract: Chiral phosphoric acid-catalysed Friedel–Crafts alkylation reactions of indoles, pyrrole and 3-(dimethylamino)phenol with racemic spiro indolin-3-ones have been realised. With 5 mol% (S)-TRIP, Friedel–Crafts adducts bearing a quaternary stereocentre were obtained in up to 99% yield and 99% ee. The reaction features readily available, stable starting materials and delivers synthetically useful but challenging products.
TL;DR: A key aspect of this method relies on the use of N,Ndimethylformamide, which was proposed to assist the activation of the secondary allylic alcohols by forming the Vilsmeier-like-intermediate 3 with the sulfamic acid and preliminary results on the enantioselective conversion of Scheme 1.
Abstract: Catalytic asymmetric allylic alkylation (AAA) is a wellestablished synthetic protocol to realize complex molecular architectures in a stereochemically defined manner. This method routinely requires preinstalled or in situ formed allylic leaving groups (i.e. acetates, carbonates, phosphates) to generate h-metal allyl complexes amenable to nucleophilic attack at the allylic termini. A conceptually simple way for improving both the economic and the environmental impact of AAA reactions would be the direct employment of allylic alcohols as precursors of the h-allyl fragment. As a matter of fact, alcohols are largely available and eco-friendly because they give water as the only by-product. Last but not least, substantial shortening of the whole synthetic process would occur because most of the common AAA partners are obtained from the corresponding alcohols. On the other hand, the poor leaving group character of the hydroxy function, combined with the possible inhibiting effect exerted by the released water on the metal catalysts, have prevented allylic alcohols from emerging as reliable key players in this field. Currently, the scenario is changing rapidly and innovative metal-catalyzed AAA methods, which include the use of alcohols, have been proposed. Such synthetic strategies exploit late-transition-metal salts/complexes through isohypsic or redox (M/M) catalysis. Although the use of allylic alcohols in catalytic enantioselective alkylation processes (i.e. amination reaction and arene alkylation) has been efficiently addressed in the recent past, the use of external activating agents to enhance the reactivity of alcohols was required. Very recently, a breakthrough in the field was provided by Roggen and Carreira, who documented the first stereoselective synthesis of primary amines from alcohols by means of sulfamic acid as an ammonia equivalent. The efficiency of new phosphoramidite [(P,olefin)2IrX] complexes was highlighted in the stereospecific displacement of enantiomerically enriched secondary alcohols by the amino group (Scheme 1 a). A key aspect of this method relies on the use of N,Ndimethylformamide, which was proposed to assist the activation of the secondary allylic alcohols by forming the Vilsmeier-like-intermediate 3 with the sulfamic acid (Scheme 2). Although the method is far from synthetic utilization, preliminary results on the enantioselective conversion of Scheme 1. Stereospecific iridium(I)-catalyzed synthesis of primary amines from allylic alcohols. Bz = benzoyl, coe = cyclooctene.
TL;DR: A significant expansion of the scope of this chemistry is reported, achieved with cobalt–phenanthroline (L1 or L2) catalysts, which allow the ortho alkylation of aromatic imines with a variety of olefins under mild reaction conditions.
Abstract: Cobalt—phenanthroline catalysts are successfully applied in the ortho-alkylation of aromatic imines with various olefins.
TL;DR: By simply running the reactions under air and solvent-free conditions using catalytic amounts of manganese dioxide, a practical and efficient N-alkylation method for a variety of sulfonamides and amines using alcohols as green alkylating reagents was developed.
TL;DR: The enantioselective alkylation of α,β-unsaturated aldehydes with stabilized carbocations as electrophiles via the activation as dienamine intermediates is described, allowing for the first enantiOSElective γ-alkylation of linear α, β-unsubstituted enals.
TL;DR: FeCl(3) in combination with t-BuOOt-Bu as an oxidant was found to be an efficient catalyst for oxidation of alkylamides to α-(tert-butoxy)alkylamides and the Friedel-Crafts alkylation.
Abstract: FeCl3 in combination with t-BuOOt-Bu as an oxidant was found to be an efficient catalyst for oxidation of alkylamides to α-(tert-butoxy)alkylamides. FeCl2 and CuCl showed, respectively, almost the same and slightly lower activities compared with FeCl3 in the tert-butoxylation of N-phenylpyrrolidone (1a), whereas no tert-butoxylated product was obtained by use of Fe(OTf)3, RuCl3, or Zr(OTf)4. FeCl3 was found to be effective also as a catalyst for the Friedel−Crafts alkylation with thus obtained α-(tert-butoxy)alkylamides. The Friedel−Crafts alkylation proceeded smoothly also in the presence of a catalytic amount of Fe(OTf)3, RuCl3, or Zr(OTf)4. In contrast, FeCl2 and CuCl, which showed certain activity toward the tert-butoxylation, failed to promote the Friedel−Crafts alkylation. Among the transition metal complexes thus far examined, only FeCl3 showed high catalytic activities for both the oxidation and the Friedel−Crafts alkylation. The bifunctionality of FeCl3 was utilized for the oxidative coupling of ...