Boron Trifluoride Etherate Research Articles

Construction of Spiro[indeno[2,1‐e]pyrrolo[3,4‐b]pyridine‐10,3′‐indoline] and Indeno[1,2‐b]pyrrolo[3,4‐e]pyridine via Three‐Component Reaction

AbstractThe three‐component reaction of β‐enamino imides, isatins and indan‐1,3‐dione in refluxing ethanol in the presence of triethylamine afforded functionalized spiro[indeno[2,1‐e]pyrrolo[3,4‐b]pyridine‐10,3′‐indolines] in good yields. The similar three‐component reaction of β‐enamino imides, aromatic aldehydes and indan‐1,3‐dione in methylene dichloride in the presence of boron trifluoride etherate resulted in the corresponding indeno[1,2‐b]pyrrolo[3,4‐e]pyridine derivatives.

Cardanol Polymerization Under Acid Conditions By Addition And Condensation Reactions

Cashew nut shell liquid (CNSL) is a byproduct of the cashew nut industry and consists predominantly of phenolic compounds that have an side chain with different degrees of unsaturation. Cardanol, one of these components, is biodegradable and widely available. Studies have revealed several polymerization reactions involving cardanol. However, the mechanisms and detailed structures of polymerization reactions have not been explored, although the final product shows different applications. In this work, we evaluated the mechanism and the products structure of the reaction of cardanol with: (i) boron trifluoride diethyl etherate (BF3O(CH2CH3)2), and (ii) formaldehyde. The characterizations were performed by FTIR, 1H NMR, SEC and TGA. The results show that the reaction of cardanol with aldehyde produces the expected like-comb structure with a long hydrocarbon pendent chain. Nevertheless, the reaction of cardanol with BF3O(CH2CH3)2 can exhibits a more complex structure since it was identified aromatic ring linkages, besides the expected polymerization through C=C.

Boron Trifluoride‐Catalyzed Synthesis of 3‐Alkylidene‐3H‐indole N‐Oxides via Tandem Reaction of Propargylic Alcohols and Nitrosobenzenes

AbstractAn atom‐economical synthesis of 3‐alkylidene‐3H‐indole N‐oxides has been developed via a tandem reaction of propargylic alcohols and nitrosobenzenes in the presence of boron trifluoride etherate (BF3⋅Et2O) as catalyst. This method offers great potential for the synthesis of biologically important 3‐alkylidene‐3H‐indole N‐oxides and related derivatives.magnified image

One-Pot Synthesis of Rotationally Restricted, Conjugatable, BODIPY Derivatives from Phthalides.

O-Ethylation of phthalides with Meerwein's reagent followed by reaction of the ensuing salts with pyrrole, results in the formation of 5-alkoxy-5-phenyl dipyrromethane derivatives, which function as ready precursors of ortho-substituted 8-aryl BODIPY derivatives by reaction with borontrifluoride etherate, an overall process that can be carried out in a one-pot operation.

Stereodivergent Mannich reaction of bis(trimethylsilyl)ketene acetals with N-tert-butanesulfinyl imines by Lewis acid or Lewis base activation, a one-pot protocol to obtain chiral β-amino acids.

We report a one-pot synthesis of chiral β2,2,3-amino acids by the Mannich addition of bistrimethylsilyl ketene acetals to N-tert-butanesulfinyl imines followed by the removal of the chiral auxiliary. The synthesis and isolation of pure β-amino acid hydrochlorides were conducted under mild conditions, without strong bases and this method is operationally simple. The stereoselective reaction was promoted by two different activation methods that lead to different stereoisomers: (1) Lewis Acid (LA) catalysis with boron trifluoride diethyl etherate and (2) Lewis Base (LB) catalysis with tetrabutylammonium difluorotriphenylsilicate. The reaction presented good diastereoselectivity with LB activation and moderate to good dr with LA catalysis. The exceptions in both protocols were imines with electron donating groups in the aromatic ring.

1,2-cis-α-Glucoside Formation from a 2-Benzyloxycarbonylamino-2-deoxy-α-D-glucopyranosyl Acetate Derivative by an Activating System That Used a Combination of Ytterbium(Ill) Triflate and a Catalytic Boron Trifluoride Diethyl Etherate Complex

1,2-cis-α-Glucoside Formation from a 2-Benzyloxycarbonylamino-2-deoxy-α-D-glucopyranosyl Acetate Derivative by an Activating System That Used a Combination of Ytterbium(Ill) Triflate and a Catalytic Boron Trifluoride Diethyl Etherate Complex

ChemInform Abstract: One‐Pot Synthesis of N‐tert‐Butylsulfinylimines and Homoallylamine Derivatives from Epoxides.

AbstractThe reaction of epoxides with tert‐butanesulfinamide in the presence of a Lewis acid, such as erbium triflate or boron trifluoride—diethyl ether, in THF as solvent, under microwave or thermal activation, produces N‐tert‐butylsulfinylimines in reasonable yields.

Metal‐Free Enantioselective Oxidative Arylation of Alkenes: Hypervalent‐Iodine‐Promoted Oxidative C−C Bond Formation

AbstractThe enantioselective oxyarylation of (E)‐6‐aryl‐1‐silyloxylhex‐3‐ene was achieved using a lactate‐based chiral hypervalent iodine(III) reagent in the presence of boron trifluoride diethyl etherate. The silyl ether promotes the oxidative cyclization, and enhances the enantioselectivity. In addition, the corresponding aminoarylation was achieved.

Metal-Free Enantioselective Oxidative Arylation of Alkenes: Hypervalent-Iodine-Promoted Oxidative C-C Bond Formation.

The enantioselective oxyarylation of (E)-6-aryl-1-silyloxylhex-3-ene was achieved using a lactate-based chiral hypervalent iodine(III) reagent in the presence of boron trifluoride diethyl etherate. The silyl ether promotes the oxidative cyclization, and enhances the enantioselectivity. In addition, the corresponding aminoarylation was achieved.

Synthesis and Analysis of Glucuronic Acid-Conjugated Metabolites of 4-Bromo-2,5-Dimethoxyphenethylamine.

In the study reported here, two glucuronic acid-conjugated metabolites of 4-bromo-2,5-dimethoxyphenethylamine (2C-B)-a ring-substituted psychoactive phenethylamine-were chemically synthesized for the first time and a method for analyzing them in urine was developed. β-D-Glucuronide of 4-bromo-2,5-dimethoxyphenylethylalcohol was successfully synthesized using methyl 2,3,4-tri-Ο-acetyl-1-O-(trichloroacetimidoyl)-α-D-glucuronate as a glucuronyl donor and boron trifluoride diethylether complex as a Lewis acid catalyst. β-D-Glucuronide of 4-bromo-2,5-dimethoxyphenylacetic acid was synthesized by condensing 4-bromo-2,5-dimethoxyphenylacetic acid and benzyl D-glucuronate followed by benzyl group deprotection based on catalytic hydrogenation. Two glucuronic acid-conjugated metabolites of 2C-B in urine were qualitatively and semiquantitatively evaluated via direct liquid chromatography/mass spectrometry (LC/MS) analysis of a diluted urine sample. The simple method proposed is expected to be useful for studying the metabolic fate of 2C-B.

Synthesis of γ-sulfonyl δ-lactones and β-sulfonyl styrenes

A facile route to the synthesis of γ-sulfonyl lactones 5 and β-sulfonyl styrenes 6 has been developed, achieving moderate to good yields via the (1) NaH mediated Michael addition of β-ketosulfones 3 and methyl acrylate in refluxing THF and (2) NaBH4 mediated stereoselective reduction/lactonization of δ-ketoesters 4 in boiling MeOH, or (3) boron trifluoride etherate mediated ring-opening of lactones 5 in MeOH at reflux.

Metal‐Free Synthesis of 3‐Arylquinolin‐2‐ones from N,2‐Diaryl‐ acrylamides via Phenyliodine(III) Bis(2,2‐dimethylpropanoate)‐ Mediated Direct Oxidative C−C Bond Formation

AbstractTreatment of N,2‐diarylacrylamides with the organoiodine(III) compound phenyliodine(III) bis(2,2‐dimethylpropanoate) [PhI(O2C‐t‐Bu)2] and boron trifluoride etherate (BF3⋅Et2O) resulted in a direct and selective oxidative C(sp2)−C(sp2) bond formation leading to a convenient assemblage, under mild conditions, of the biologically important 3‐arylquinolin‐2‐one skeleton. Differing from the five‐membered oxindole products from oxidative cyclizations mediated by transition metals, this metal‐free approach realized a direct annulation of the N‐arylacrylamide into a six‐membered 3‐arylquinolin‐2‐one skeleton.magnified image

Generation of oxodiazonium ions 6. Unexpected formation of tetrazole 1-oxides

(E)-2-[2,2-Bis(tert-butyl-NNO-azoxy)-1-(methylsulfinyl)vinyl]-1-isopropoxydiazene 1-oxide reacts with boron trifluoride etherate (BF3•Et2O) producing 2-tert-butyl-N-nitro-2H-tetrazolo-5-carboxamide 4-oxide and 2-tert-butyl-2H-tetrazolo-5-carbonitrile 4-oxide but not the expected 1,2,3,4-tetrazine 1,3-dioxide derivative. This reaction direction can be explained by cationic domino cyclization, the key stage of which is coupling of the oxodiazonium ion with the geminal MeS(O) group. Structure of N-nitrocarboxamide was confirmed by X-ray diffraction analysis.

1,5-Diaryl-3-oxo-1,4-pentadienes based on (4-oxopiperidin-1-yl)(aryl)methyl phosphonate scaffold: synthesis and antitumor properties

Novel 3,5-bis(arylidene)-4-piperidones modified with diethyl[(aryl)methyl]phosphonate moiety attached to the piperidone nitrogen atom have been synthesized by crotonic condensation of aromatic aldehydes with diethyl[(4-oxopiperidin-1-yl)(aryl)methyl]phosphonates in the presence of LiClO4/Et3N system or acetonitrile solution of boron trifluoride etherate. The synthesized phosphonate derivatives of 3,5-bis(arylidene)-4-piperidone series displayed inhibitory properties toward RD, PC3, HCT116, and MCF7 human cancer cell lines with IC50 values in the range of 2.5–8.5 μM, as assessed by an in vitro 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay.

WAGNER–MEERWEIN REARRANGEMENT IN 2,6a-EPOXYOXIRENO[ e ]ISOINDOLE SERIES

A cation-catalyzed Wagner–Meerwein skeletal rearrangement in octahydro-2,6a-epoxyoxireno[ e ]isoindole series was studied. It was shown that the reaction proceeds ambiguously when effected by boron trifluoride etherate in acetic anhydride: the target 4,5-bis(acetoxy)-4,6-epoxycyclopenta[ c ]pyridines as well as the products of their further degradation, cyclopenta[ c ]pyridines, were isolated from the reaction mixture in 10–15% yields as single diastereomers. Authors: Vladimir P. Zaytsev*, Fedor I. Zubkov, Mar'yana A. Nadirova, Dmitriy F. Mertsalov, Eugeniya V. Nikitina, Roman A. Novikov, Alexey V. Varlamov

Luminescent tetrahydrodibenzo[a,i]phenanthridin-5-yl)phenol-boron complexes (borophenanthridines)

A series of weakly emissive, exited state intramolecular proton transfer active tetrahydrodibenzo[a,i]phenanthridin-5-yl)phenols were efficiently synthesized using 2-tetralone and substituted salicylaldehydes. These dyes were smoothly coordinated with boron trifluoride diethyletherate resulting in π-conjugated and rigid tetracoordinated boron-phenanthridine complexes. The complexes were highly emissive in solution and solid states with large Stokes shift values ranging from 6190 to 10410 cm−1 and moderate fluorescence quantum yields. A systematic photophysical and solvatochromism studies revealed that the intramolecular charge transfer process was more effective in borophenanthridines than with others, which was supported by DFT study. Further, the electrochemical studies testified the high electron-accepting ability of these boron complexes.

Lewis Acid Mediated [3+2] Coupling of Masked Benzoquinones with Styrenes: Facile Synthesis of 2,3-Dihydrobenzofurans

We have developed an efficient, simple, mild, and rapid method for the construction of dihydrobenzofuran derivatives by the [3+2] coupling of masked o-benzoquinones with styrene derivatives triggered by boron trifluoride diethyl etherate. This new [3+2] coupling protocol proceeds smoothly to afford dihydrobenzofuran derivatives in good to high yields within one minute. The method was extended to cycloaddition of p-benzoquinone monoketal with styrenes.

Contraction of the cyclohexene ring in the Diels–Alder adduct of levoglucosenone with piperylene

Diels–Alder adducts of levoglucosenone with piperylene were subjected to allylic oxidation–epoxidation, followed by successive functionalization of the α- and β-positions, and transformations of the resulting 1,2-epoxy derivatives under the action of boron trifluoride–diethyl ether complex and bases were studied. The most efficient was the Wagner–Meerwein rearrangement of the α-hydroxy derivative with formation of a fused cyclopentane in 39% yield.

Reactions of aromatic compounds with xenon difluoride

Reactions of substituted benzenes C6H5R (R = Me, F, Cl, Br, CF3, NO2) with xenon difluoride in the presence of boron trifluoride–diethyl ether complex in weakly acidic (1,1,1,3,3-pentafluorobutane) and weakly basic media (acetonitrile) have been studied. These reactions lead to the formation of fluorobenzene derivatives FC6H4R (isomer mixture) together with isomeric difluorobenzenes and fluorinated and non-fluorinated biphenyls. The results have been compared with previously reported data obtained in other solvents using other catalysts.

ChemInform Abstract: Efficient Synthesis of Dimeric Oxazoles, Piperidines and Tetrahydroisoquinolines from N‐Substituted 2‐Oxazolones.

AbstractDifferent types of N‐substituted 2‐oxazolone substrates are subjected to a boron trifluoride etherate promoted reaction under slightly modified conditions to produce the title heterocycles (investigation and discussion of the cascade mechanisms).