Efficient utilization of tetrabutylammonium bifluoride in halofluorination reactions

Camps, Francisco; Chamorro, Ester; Gasol, V.; Guerrero, Ángel

doi:10.1021/jo00279a013

Cited by 54 publications

(17 citation statements)

References 2 publications

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“…The structures of these 1,2-vicinal dibromides were also established on the basis of their spectral data. The literature reveals the formation of dihalo derivatives during the haloflourination reaction of a variety of alkenes, and the mechanism for this side reaction had also been postulated (7). Thus, a new synthetic strategy to prepare ethoxylates from olefins has been proposed.…”

Section: Resultsmentioning

confidence: 99%

Synthesis of β‐bromoethoxylates and β‐chloroethoxylates from olefinic fatty methyl esters

Singh

2006

J Surfact & Detergents

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Olefinic fatty methyl esters [undec-10-enoate (1 1), octadec-Z-9-enoate (2 2), methyl-12 hydroxy octadec-Z-9-enoate (3 3)], on reaction with an N-halosuccinimide (4 4--5 5)-i.e., N-bromosuccinimide (NBS; 4 4) or N-chlorosuccinimide (NCS; 5 5)-in the presence of diols such as mono-, di-, tri-, and tetraethylene glycols (6 6--9 9), gave the respective β-bromo-or β-chloroethoxylates (1 11 1--3 34 4).Paper no. S1476 in JSD 9, 51-56 (Qtr. 1, 2006)., ethylene glycols (mono-, di-, tri-, and tetra-), methyl esters, octadec-Z-9-enoic acid, polyethers, undec-10-enoic acid.Alkyl ethoxylates are well known for their use as nonionic surfactants (1). The ethoxylates also serve as starting materials for the formation of alkyl ether sulfate, a product used extensively for the manufacture of shampoos. These ethoxylates are generally prepared by an ethoxylation reaction of fatty alcohol with ethylene oxide. The cohalogenation of alkenes with halogens and nucleophilic solvents such as water, diomethylsulfoxides, dimethylformamide, carboxylic acids, alcohols, nitriles, and ethers is well documented (2). Dinulescu et al.(3) also reported the cohalogenation with ethereal solvents such as diethyl ether, tetrahydrofuran, dioxane, and ethylene oxide, leading to substituted β-haloether. A recent report by Younes et al. (4) describes the reaction of Nbromosuccinimide (NBS) and dimercaptoethane in diethyl ether to form β,β ′ -dibromodithioethers. To date, no reports have appeared on the utilization of cohalogenation reactions in fatty acid or vegetable oil chemistry. However, Ahmed and Singh (5) reported the cohalogenation of carboxylic acids on fatty methyl esters in a previous work. In the present study, we attempted to use the cohalogenation reaction of NBS and N-chlorosuccinimide (NCS) on olefinic fatty methyl esters to prepare potentially useful β-bromoethoxylates and β-chloroethoxylates. EXPERIMENTAL PROCEDURESMaterials and methods. Undec-10-enoic acid, octadec-Z-9-enoic acid, and NCS were purchased from Loba Chemicals (Mumbai, India). NBS was purchased from Central Drug House (New Delhi, India). 12-Hydroxy octadec-Z-9-enoic acid was isolated from castor oil using the partitioning method of Gunstone (6). Mono-, di-, tri-, and tetraethylene glycols were procured from M/S Sisco Chem. (Bombay, India) and were air-dried in an oven at a temperature of 120°C for 4 h, followed by cooling and storage in a desiccator. Thin-layer chromatography (TLC) was carried out on silica gel G-coated (0.25-mm thick) plates with petroleum ether/diethyl ether/acetic acid (80:20:1 or 60:40:1) as the mobile phase. Spots were visualized by iodine. Infrared spectra were recorded on a Shimadzu FT-IR 8400s instrument. 1 H nuclear magnetic resonance (NMR) spectra were recorded on a Brucker-200 spectrometer, and 13 C NMR spectra were recorded on a Jeol FT-NMR spectrometer at 300 MHz (AL-300). Mass spectra were recorded on a Jeol SX-102 [electron impact/chemical ionization/fast atom bombardment (FAB)] at the Central Drug Research Institute (CDRI) in Lukhnow, India. G...

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Section: Resultsmentioning

confidence: 99%

Synthesis of β‐bromoethoxylates and β‐chloroethoxylates from olefinic fatty methyl esters

Singh

2006

J Surfact & Detergents

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“…The structure of these 1,2-vicinal dibromides/dichlorides has also been established on the basis of their spectral data. Literature reveals the formation of dihalo derivatives during the halofluorination reaction of a variety of alkenes; the mechanism for this side reaction has also been postulated (16). …”

Section: Resultsmentioning

confidence: 99%

“…The solution was dried over anhydrous sodium sulfate. The evaporation and subsequent fractionation on silica gel (60-120 mesh) column chromatography using hexane, hexane:chloroform (90:10 to 50:50), chloroform:methanol (98:2) (step-wise increasing polarity elution method) yielded a white crystalline mass having a melting point of 122°C, characterized as succinimide (7), followed by 1,2-dihalides (14)(15)(16)(17)(18)(19) as minor product and the respective β-bromothioethoxylates or β-chloroethioethoxylates (Scheme 1; [8][9][10][11][12][13] in quantitative yield. Inseparable positional isomers were formed in all cases.…”

Section: Methodsmentioning

confidence: 99%

N‐halosuccinimide‐mercaptoethanol cohalogenation of olefinic fatty methyl esters: Synthesis of β‐halo thioethoxylates

Singh

2006

J Surfact & Detergents

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Olefinic fatty methyl esters, undec-10-enoate (1), octadec-Z-9-enoate (2), methyl-12 hydroxy octadec-Z-9-enoate (3), on reaction with N-halosuccinimides (4,5), that is, N-bromosuccinimide (4) or N-chlorosuccinimide (5) and 2-mercaptoethanol (6) in benzene, gave β-bromo-or β-chlorothioethoxylates (8-13). β-Halothioethoxylates so formed were acetylated with acetyl chloride in CH 2 Cl 2 to form the respective acetylated products (20-25).

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“…The absolute configuration of 36 was determined to be (R) by comparison of its optical rotation and HPLC retention time with those of an independently prepared sample of (R)-36. The reference compound (R)-36 was synthesized via bromination of trinorbornene followed by carbonylation [36] [37] to give 37. Racemic 37 was partially resolved by recrystallization of its salt with ()-(R)-a-methylbenzylamine and converted to the amine (R)-38 via Curtius degradation with diphenylphosphoryl azide [38].…”

Section: Figure Catalysts and Ligandsmentioning

confidence: 99%

Desymmetrization ofmeso-N-Sulfonylaziridines with Chiral Nonracemic Nucleophiles and Bases

Müller

Nury

2001

HCA

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The cyclohexene-derived aziridine 7-tosyl-7-azabicyclo[4.1.0]heptane (1) reacts with Grignard reagents in the presence of chiral nonracemic Cu-catalysts to afford sulfonamides 3a ± e (Scheme 3) in up to 91% ee under optimized conditions ( Table 2). No activation of the aziridine by Lewis acids is required. The reaction may be extended to other bicyclic N-sulfonylated aziridines, but aziridines derived from acyclic olefins, cyclooctene, and trinorbornene are unreactive under standard conditions (Scheme 5). Exposure of 1 to s-BuLi in the presence of (À)-sparteine (2.8 equiv.) affords the allylic sulfonamide 31 in 35% yield and 39% ee (Scheme 6). Under the same conditions, the aziridines 33 and 35 yield products 34 and 36 derived from intramolecular carbenoid insertion with 75 and 43% ee, respectively.Introduction. ± Aziridines are the N-analogues of epoxides, and as such, are attractive intermediates for a variety of transformations affording N-containing products [1]. In this context, the synthesis of chiral nonracemic aziridines is of particular interest. However, although chiral aziridines are accessible via asymmetric aziridination of olefins [2], the methods currently available are limited. Alternatively, optically active products derived from ring opening of achiral aziridines are, in principle, accessible via their enantioselective desymmetrization, in analogy with the widely and successfully applied desymmetrization of achiral epoxides [3]. This latter reaction may be effected via a-deprotonation [4], b-deprotonation [5], or via nucleophilic ring opening under stoichiometric [6] and catalytic conditions [7]. Several procedures for selective ring opening of aziridines by nucleophilic substitution are known. N-Alkyl-or N-(arylalkyl)aziridines undergo ring opening in the presence of catalytic amounts of lanthanide ions, in particular Yb III [8], and react with aromatic amines in the presence of Sn II or Cu II catalysts [9]. Enantioselective opening of Nalkylaziridines with up to 94% ee has been reported for their reaction with azidotrimethylsilane (Me 3 SiN 3 ) and a tridentate Schiff-base chromium complex [10]. A catalytic method involving thiols in the presence of ZnEt 2 and an optically active tartrate for desymmetrization of N-acylated aziridines has recently been published [11]. Ring opening of aziridines by organometallic reagents, in turn, has been known since 1985, when Eis and Ganem reported the opening of N-alkylaziridines by organocuprates under stoichiometric conditions in the presence of BF 3 [12]. Subsequently, Baldwin et al. found that N-sulfonated aziridines do not require BF 3 to react with organocuprates [13], and several applications of this observation appeared [14] [15], including achiral opening of N-phosphinylaziridines with organocuprates [16].In the context of our ongoing research on catalytic aziridination of olefins [2a][17], a certain number of chiral and meso-N-sulfonylaziridines were synthesized via Rh II -

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Efficient utilization of tetrabutylammonium bifluoride in halofluorination reactions

Cited by 54 publications

References 2 publications

Synthesis of β‐bromoethoxylates and β‐chloroethoxylates from olefinic fatty methyl esters

Synthesis of β‐bromoethoxylates and β‐chloroethoxylates from olefinic fatty methyl esters

N‐halosuccinimide‐mercaptoethanol cohalogenation of olefinic fatty methyl esters: Synthesis of β‐halo thioethoxylates

Desymmetrization ofmeso-N-Sulfonylaziridines with Chiral Nonracemic Nucleophiles and Bases

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