Triflic Imide Research Articles

Triflic Imide‐Catalyzed Glycosylation of Disarmed Glycosyl ortho‐Isopropenylphenylacetates and ortho‐Isopropenylbenzyl Thioglycosides

AbstractGlycosylation reaction involving the coupling of a glycosyl donor with a glycosyl acceptor is one of the cornerstones of chemical preparation of pure glycans and glycoconjugates of biological relevance. Catalytic glycosylation of glycosyl ester donors and thioglycosides is an attractive but underexplored topic in carbohydrate chemistry. Herein, triflic imide (Tf2NH)‐catalyzed glycosylation of various O‐, S‐, and C‐nucleophiles has been achieved using disarmed glycosyl ortho‐isopropenylphenylacetates (GIPPAs) and ortho‐isopropenylbenzyl thioglycosides as glycosylating agents. The reactions proceed under mild conditions to give the desired glycosides in good‐to‐excellent yields. Of particular note, the comparable reactivity for the α‐isomers and the β‐ones of GIPPAs is observed. The mechanistic investigation demonstrates that the isopropenyl group is essential for the reaction and its preferential protonation triggers the reaction. This work provides another member to the arsenals of glycosyl ester and thioglycoside donors suitable for acid‐catalyzed glycosylation to create various glycosidic bonds.

Reversal of Regioselectivity in Nucleophilic Difluoroalkylation of α,β-Enones Employing In Situ-Formed Sterically Encumbered Silylium Catalyst.

An efficient approach for the reversal of regioselectivity in the nucleophilic introduction of difluorinated carbanion into α,β-enones has been developed via a silylium catalysis. The strong electron-withdrawing properties and bulky substituents of in situ-generated silyl triflic imide catalyst is the key for the 1,4-addition reaction to proceed smoothly. The synthetic utility is highlighted by the further use of this method for the synthesis of 2,4,6-triarylsubstituted 3-fluoropyridines in a one-pot manner.

Brønsted Acid‐Catalyzed Cyclopropanation of Indoles Using α‐Aryl‐α‐diazoacetates

AbstractMetal‐free cyclopropanation of N‐protected indoles with α‐aryl‐α‐diazoacetates proceeded by using a catalytic amount of triflic imide as a Brønsted acid catalyst. The use of a catalytic amount of methyl phenylacetate improved the efficiency of the Brønsted acid‐catalyzed cyclopropanation. A reaction mechanism including C‐protonation of diazoacetates with HNTf2, followed by formal [3+2] cycloaddition with indoles and 1,3‐rearrangement was proposed for the cyclopropanation.

ChemInform Abstract: Synthesis of Multisubstituted Silyloxy‐Based Donor—Acceptor Cyclobutanes by an Acid‐Catalyzed [2 + 2] Cycloaddition

AbstractReview: [33 refs.

Synthesis of Multisubstituted Silyloxy‐based Donor‐Acceptor Cyclobutanes by an Acid‐Catalyzed [2+2] Cycloaddition

AbstractThis account summarizes our recent efforts on the acid‐catalyzed [2+2] cycloaddition of silyl enol ethers with α,β‐unsaturated esters, giving donor‐acceptor (D‐A) cyclobutanes and their related reactions. The cycloaddition generally produces multisubstituted cyclobutanes in good yields with high diastereoselectivity. We found that aluminum Lewis acids and triflic imide (Tf2NH) had good catalytic activity. The retro [2+2] cycloaddition proceeded at higher reaction temperatures, and in some cases, diastereoselectivity switching of cycloadducts was observed. A microflow protocol was established for Tf2NH‐catalyzed [2+2] cycloaddition. Although the cycloaddition usually requires cryogenic conditions in a batch reactor, the microreactor system enabled the production of D‐A cyclobutanes, even at ambient temperature. [2+2] Cycloaddition of allylsilanes and alkyl enol ethers, instead of silyl enol ethers, afforded the corresponding D‐A cyclobutanes.

トリフリックイミドのオート·タンデム触媒作用を利用する有機合成

omino reactions have received great attention as efficient synthetic methodologies to construct structurally complex molecules from simple materials in a single operation. Recently a new concept, “tandem catalysis” in domino reactions has been proposed. Tandem catalysis is categorized into three subclasses: Orthogonal, auto-, and assisted-tandem catalysis. Auto-tandem catalysis is defined as a process in which one catalyst promotes more than two mechanistically different reactions in a single vessel.It has been discovered by several researchers including us that triflic imide (Tf2NH) activates a variety of chemical transformations, such as Mukaiyama-aldol reaction, conjugate addition, cycloadditions and so on. This account summarizes our recent development of auto-tandem catalysis of triflic imide.

ChemInform Abstract: Selective Synthesis of Polysubstituted Dihydroquinolines and α,β‐Unsaturated Amidines by a Catalytic Reaction of Ynamides with Ketimines.

Ynamides reacted with benzophenone imines in the presence of triflic imide as a catalyst. Ynamides bearing a sulfonamide moiety gave the corresponding 2-amino-3,4-dihydroquinolines selectively in good to high yields. In contrast, yne-carbamates gave the corresponding α,β-unsaturated amidines exclusively. These methods permit simple preparation of sterically crowded polysubstituted quinolines and α,β-unsaturated amidines.

Selective Synthesis of Polysubstituted Dihydroquinolines and α,β-Unsaturated Amidines by a Catalytic Reaction of Ynamides with Ketimines

Ynamides reacted with benzophenone imines in the presence of triflic imide as a catalyst. Ynamides bearing a sulfonamide moiety gave the corresponding 2-amino-3,4-dihydroquinolines selectively in good to high yields. In contrast, yne-carbamates gave the corresponding α,β-unsaturated amidines exclusively. These methods permit simple preparation of sterically crowded polysubstituted quinolines and α,β-unsaturated amidines.

Facile isomerization of silyl enol ethers catalyzed by triflic imide and its application to one-pot isomerization–(2 + 2) cycloaddition

A triflic imide (Tf2NH) catalyzed isomerization of kinetically favourable silyl enol ethers into thermodynamically stable ones was developed. We also demonstrated a one-pot catalytic reaction consisting of (2 + 2) cycloaddition and isomerization. In the reaction sequence, Tf2NH catalyzes both of the reactions.

ChemInform Abstract: Formal [3 + 3] Cycloaddition of Silyl Enol Ethers Catalyzed by Triflic Imide: Domino Michael Addition—Claisen Condensation Accompanied with Isomerization of Silyl Enol Ethers.

AbstractA triflimide catalyzed formal [3 + 3] cycloaddition of silyl enol ethers with acrylates is described as a new domino reaction.

Room‐Temperature, Acid‐Catalyzed [2+2] Cycloadditions: Suppression of Side Reactions by using a Flow Microreactor System

Added value: The [2+2] cycloaddition of silyl enol ethers with α,β-unsaturated esters, catalyzed by the superstrong acid triflic imide (Tf2NH), at room temperature in a flow microreactor system is reported. The micororeactor method achieves the [2+2] cycloaddition of unstable silyl enol ethers and acrylates, which is unsuccessful in batch reactors, even at room temperature.

Thieme Chemistry Journal Awardees - Where Are They Now? Triflic Imide Catalyzed Cycloaddition Reactions

This Account summarizes our recent development of triflic imide(Tf 2 NH)-catalyzed cycloaddition and cascade reactions. Reactionsof electron-rich olefins, possessing a silyl group, with α,β-unsaturatedcarbonyl compounds afforded highly substituted cyclobutanes, cyclopentanes,and bicyclo[4.2.0]octanes in good to excellentyields. In the reactions, Tf 2 NH acts as a precatalystto produce a strong Lewis acid, silyl triflic imide, which activatesthe cycloaddition reactions. Reactions of electron-rich olefinswith aldimines furnished highly substituted heterocycles such aspiperidines, quinolines, and pyrrolidines. In these cases, Tf 2 NHacts as a strong Bronsted acid. Moreover, it was foundthat Tf 2 NH can catalyze more than two mechanisticallydistinct reactions in one pot (tandem catalysis), so that a varietyof molecular skeletons can be constructed in a single operation. 1 Introduction 2 (2+2) Cycloaddition of α,β-UnsaturatedEsters 2.1 (2+2) Cycloadditon with Silyl Enol Ethers 2.2 (2+2) Cycloaddition with Allylsilanes 3 (3+2) Cycloaddition of Donor-Acceptor Cyclopropanes 4 Multicomponent Reaction: Cascade (4+2)-(2+2)Cycloaddition 5 Cycloaddition of Imines 5.1 Aza-(4+2) Cycloaddition with 2-Siloxydienes 5.2 Cascade Povarov-Hydrogen-Transfer Reaction withAllylsilanes 5.3 Aza-(3+2) Cycloaddition with α,α-Dimethylallylsilanes 6 Conclusions

ChemInform Abstract: Triflic Imide Catalyzed [3 + 2] Cycloaddition of Aldimines with α,α‐Dimethylallylsilane.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: A Catalytic Method for the Preparation of Polysubstituted Cyclopentanes: [3 + 2] Cycloaddition of Vinylidenecyclopropanes with Activated Olefins Catalyzed by Triflic Imide.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Triflic Imide Catalyzed [3+2] Cycloaddition of Aldimines with α,α-Dimethylallylsilane

Tf 2 NH-catalyzed [3+2] cycloaddition of N-aryl imines with a,a-dimethylallylsilane to give substituted pyrrolidines is described. We have found the mode of cycloaddition depends upon α-substituents of allylsilanes.

ChemInform Abstract: [2 + 2] Cycloaddition Reaction of Alkyl Enol Ethers with Acrylates by in situ Generated Silyl Triflic Imide Catalyst.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

A Catalytic Method for the Preparation of Polysubstituted Cyclopentanes: [3+2] Cycloaddition of Vinylidenecyclopropanes with Activated Olefins Catalyzed by Triflic Imide

[3+2] Cycloadditions of vinylidenecyclopropanes (VDCPs) with electron-deficient olefins, such as methyl vinyl ketone (MVK) and acrylaldehyde, proceed smoothly in the presence of a catalytic amount of triflic imide (Tf(2)NH) to give the corresponding functionalized cyclopentanes in good to high yields.

FeCl3-Catalyzed Pechmann Synthesis of Coumarins in Ionic Liquids

The synthesis of coumarin derivatives via Pechmann reaction using anhydrous FeCl3 as Lewis acid catalyst in ionic liquid medium has been carried out. The best results were obtained (yields as high as 89%) with ionic liquids having bis(triflic)imide as a counteranion. The ionic liquid could easily be recovered and reused.

(2+2) Cycloaddition Reaction of Alkyl Enol Ethers with Acrylates by in Situ Generated Silyl Triflic Imide Catalyst

We describe here (2+2) cycloaddition reaction of alkyl enol ethers with acrylates catalyzed by triethylsilyl triflic imide (Et3SiNTf2), which was in situ generated from triethylsilane and triflic imide. The reaction efficiently provides substituted cyclobutanes bearing alkoxy function in a stereoselective manner.

Cascade and One‐Pot Processes Providing Substituted Quinolines from Aldimines and Allylsilanes: Auto‐Tandem Catalysis of Triflic Imide.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.