Pyrrolidinium acetate

Pyrrolidinium acetate Piperidinium -Isoxazolium salts Trialky loxonium salt Amidinium salts Ketenimines Benzaldoxime Hy dr azobenzene Diazo compounds Diazomethane, Phenyl-diazomethane Ethyl diazoacetate K-methyldiazotate Hexamethylenetetramine Azo compds., Azobenzene Acylazo compds. Azodicarboxamide ROOC-N N-COOK Azodiisobutyronitrile Triazenes Diazonium fluoro-borates... 

Pyrrolidinium acetate Isomeric 2-cyclohexenones from 1,5-dioxo compds. Regiospecific ring closure... 

Pyrrolidinium acetate Piperidinium acetate Isoxazolium salts Trialkyloxonium salt Amidinium salts Ketenimines Hydrazobenzene Diazo compounds Diazomethane, Phenyl-diazomethane K-methyldiazotate Hexamethy lene-tetramine Azo compds,. Azobenzene A zodicarboxamide ROOC-N N-COOR Azodiisobutyronitrile Triazenes Azidinium salts p-Nitrobenzene-diazonium sulfate Sulfanilic acid, diazotized... 

Pyrrolidinium acetate Piperidinium acetate Isoxazolium salts Trialky loxoniiim salt... 

Compendial reviews state that rocuronium bromide had been identified as having eight different impurities, which are labeled as impurities A, B, C, D, E, F, G, and H. Impurity A (i.e., related compound A) is 3a-hydroxy-2/i (morpholin-4-yl)-16/ -(pyrrolidin-l-yl)-5a-androstan-17/ -yl acetate impurity B (i.e., related compound B) is l-[3a,17/i-bis(acetyloxy)-2/i-(morpholin-4-yl)-5a-androstan-16/i-yl]-l-(prop-2-enyl)pyrrolidinium impurity C (i.e., related compound C) is l-[3a,17/i-dihydroxy-2/i-(morpholin-4-yl)-5a-androstan-16/ -yl]-l-(prop-2-enyl)pyrrolidinium and impurity D (i.e., related compound D) is l-[3a-(acetoxy)-17/J-hydroxy-2/J-(morpholin-4-yl)-5x-androstan-16/j-yl]-l-(prop-2-enyl)pyrrolidinium impurity E (i.e., related compound E) is l-[17/ -(acetoxy)-3a-hydroxy-2/ -(pyrrolidin-l-yl)-5a-androstan-16/)-yl]-l-(prop-2-enyl)pyrrolidinium impurity F (i.e., related compound F) is l-[3a,17/ -bis(acetiloxy)-2/ -(pyrrolidin-l-yl)-5a-androstan-16/i-yl]-l-(prop-2-enyl)pyrrolidinium impurity G (i.e., related compound G) is 2/)-(morpholin-4-yl)-16/i-(pyrrolidin-l-yl)-5a-androstane-3a,17/i-diol and impurity H (i.e., related compound H) is l-[17/i-(acetyloxy)-2-(morpho-lin-4-yl)-3-oxo-57-androst-l-en-16/i-yl]-l-(prop-2-enyl)pyrrolidinium [5-7], The molecular structure of rocuronium bromide is shown in Fig. 6.1, while the structures of the known impurities are illustrated in Fig. 6.2. 

A mixture of 7-[(Z)-2-ethoxyimino-2-(2-tritylaminothiazol-4-yl)acetamido]-3-iodomethyl-3-cephem-4-carboxilate (4.5 g, 4.83 mmoles) and N-methylpyrrolidine (0.65 ml, 6.28 mmoles) in CH2CI2 (45 ml) was stirred at room temperature for 20 min. Ether (300 ml) was added to the mixture to separate the quaternary salt of the blocked cephalosporin, which was collected by filtration and treated with 90% trifluoroacetic acid (TFA) (40 ml) at room temperature for 1 hour. The mixture was then evaporated under reduced pressure below 20°C. The residue was triturated with ether to give the TFA salt of 7-[(Z)-2-methoxyimino-2-(2-aminothiazol-4-yl)acetamido]-3-[(l-methyl-l-pyrrolidinium)methyl]-3-cephem-4-carboxylate (2.40 g), which was dissolved in methanol (5 ml) and treated with 1 M solution of sodium-2-ethylhexoate in ethyl acetate (8 ml) at room temperature for 30 min. After the addition of ethyl acetate (100 ml), the precipitate (1.94 g) formed was collected by filtration. HPLC analysis showed that the crude product was 7% pure with a 1 8 ratio of the S3 isomer to the S2 isomer. Purification of the product by HPLC was repeated three times (Lichrosorb RP-18, eluted with 5% aqueous methanol or 0.01 M ammonium phosphate buffer (pH 7.2 containing 5% of methanol) to give 35 mg (1.5%) of the title product as a colorless powder of 7-[(Z)-2-methoxyimino-2-(2-aminothiazol-4-yl)acetamido]-3-[(l-methyl-l-pyrrolidinium)methyl]-3-cephem-4-carboxylate. Estimated purity (by HPLC) 90%. M.p. 150°C (dec.). 

Separation science focuses on room temperature ionic liquids (RTlLs), salts that are liquid at ambient temperature. They have been studied as extracting solvents, stationary and mobile phases, mobile phase additives, and other uses. Common RTILs consist of a bulky nitrogen- or phosphorus-containing organic cation (pyridinium or pyrrolidinium, alkyl-imidazolium, ammonium or phosphonium) and a variety of organic and inorganic anions (triflate, dicyanamide, trifluoroacetate, acetate trifluo-romethylsulfate, nitrate, perchlorate, bromide, chloride, chloroaluminate, tetrafluo-roborate, hexafluorophosphate). 

Concomitant to the enhancement of the signal for C-3 in the C NMR spectrum, the signals for H2 and H4 decreased in the H-NMR spectrum of all the tropine moieties compared with those in authentic samples. This indicates the incorporation of deuterium at C2 and C4 derived from C Hj CXX)". As the diminution of the signals for H2 and H4 was not identical at both positions, we suppose a sequential incorporation of labeled acetate (example given in Fig. 15b). From these data we assume that the biosynthesis from N-methyl-pyrrolidinium ion to tropine is a two-step process which does not involve a four carbon unit (acetoacetyl coenzyme A) but two units of acetyl coenzyme A, which were added sequentially as has been suggested for the biosynthesis of cocaine [28, 37]. On the other hand it has been reported that l,2- C2-acetate was incorporated with an equal efficiency at C2 and C4 by non-transformed root cultures of H. albus [36]. Further investigations are required to clarify this matter. 

Method A A 10 mL Schlenk tube equipped with a stirrer bar was charged with oxime (0.2 mmol), pyrrolidinium perchlorate (6.9 mg, 0.04 mmol, 20 mol%), and Cul (7.6 mg, 0.04 mmol, 20 mol%). The Schlenk tube was quickly evacuated and refilled with N2 three times, followed by the addition of unsaturated aldehyde (0.3 mmol, 1.5 equiv.) and DMSO (1 mL). The Schlenk tube was sealed with a Teflon screwcap and then the reaction mixture was stirred at 60°C for 16 h. Upon cooling to room temperature, the reaction mixture was diluted with 5 mL of ethyl acetate and filtered through a pad of silica gel with additional ethyl acetate (15 mL) as the eluent. The filtrate was washed with water (10 mL), dried over Na2S04, and concentrated under reduced pressure. The residue was purified by flash chromatography on silica gel to afford the pyridine derivative. 

Eniminium salts have been shown to be efficient protecting groups for the A -3-keto moiety in the synthesis of steroids oxygenated at C-17 and C-21. Thus the pyrrolidinium perchlorate formed from progesterone yields a 17-enol acetate... 

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