The reaction of an aromatic heterocycle with a proton is called a protonation. One of articles about this theory is 《Identification of two chromogens in the Elson-Morgan determination of hexosamines. A new synthesis of 3-methylpyrrole. Structure of the “”pyrrolenephthalides””》. Authors are Cornforth, J. W.; Firth, M. E..The article about the compound:3-Methyl-1H-pyrrolecas:616-43-3,SMILESS:CC1=CNC=C1).Recommanded Product: 616-43-3. Through the article, more information about this compound (cas:616-43-3) is conveyed.
The substance producing most of the color with Ehrlich’s reagent in the Elson-Morgan assay of hexosamines is shown to be 2-methylpyrrole (I); 3-acetyl-2-methylpyrrole (II) is also formed. A synthesis of 3-methylpyrrole (III) in 4 steps from CH2:CMeCH2Cl (IV) is described. Infrared spectra indicate that the condensation products of pyrroles with ο-C6H4(CO)2O (V) are benzo[f]pyrrocoline-5,10-diones; several of these are described. D-Glucosamine-HCl (VI) (21.6 g.) in 800 cc. H2O was added to an aqueous solution (2200 ml.) containing 106 g. Na2CO3, 19.6 g. Ac2CH2, and 200 ml. N HCl, the mixture at pH 9.75 in 2 portions heated on steam baths under reflux condensers, heating continued 20 min., the solutions cooled below 30°, combined, distilled at 20 mm., and the receiver cooled, until the distillate gave no color with Ehrlich’s reagent. The distillate (450 ml.) saturated with NaCl, extracted with Et2O, shaken once with 2N NaOH and H2O, the combined aqueous and alk. solutions reëxtd. with Et2O, the extracts evaporated at -10°/30-40 mm., the residue distilled at room temperature and 1 mm. gave 650 mg. I, b766 138-46°. I remained colorless in N at -5° but darkened in air. The infrared spectrum was identical with that of authentic I. The residual liquors after collection of the aqueous distillate combined, heated 45 min., then distilled, the pyrrole precipitated as the Hg complex, the solid suspended in N Na2CO3, and decomposed with H2S gave 40 mg. I. The aqueous reaction mixture from I extracted continuously 24 hrs. with Et2O, and the product distilled at 0.6-0.7 mm. gave a product which sublimed above 100°/0.05 mm., the sublimate suspended in 1:1 Et2O-ligroine, and the solid collected gave 130 mg. II, m. 94-5° (ligroine), ν 1620 cm.-1 in KCl, and 1660 cm.-1 in CCl4. Aminoacetal (3 g.) with 1 ml. H2O added dropwise in the cold to 18 g. HCl, after 5 hrs. at room temperature the solution neutralized to methyl orange, 1.39 g. Ac2CH2 added at once, the pH adjusted to 10, after 24 hrs. at 5° the mixture saturated with salt and extracted with Et2O, the Et2O concentrated, and the residue sublimed below 100°/0.5 mm. and crystallized gave II. II would not form a semicarbazone or 2,4-dinitrophenylhydrazone. Pyrrole-2-aldehyde (5 g.) refluxed 15 min. with 10 g. KOH, 7.5 ml. 90% N2H4.H2O, and 100 ml. O(CH2CH2OH)2, the mixture heated so that I slowly distilled (with some H2O, N2H4, and glycol) (after 4-5 hrs. the condensate was weakly Ehrlich pos.), a little H2O added to the distillate, the lower layer saturated with NaCl, and extracted with Et2O gave 3.65 g. I. 2-Acetylpyrrole (1.5 g.) similarly gave 0.81 g. 2-ethylpyrrole, b20 65°. VI (250 μg.) in 5 ml. H2O heated 25 min. in a stoppered flask immersed in a bath at 95-100° with 5 ml. of a solution of 1 ml. Ac2CH2 in 50 ml. 0.5N Na2CO3, two 1-ml. samples (O1,O2) were withdrawn, the remainder concentrated at 20 mm., the thawed distillate diluted with 8 ml. H2O and a 1-ml. portion (D) taken. The residue also diluted to 8 ml. with H2O and two 1-ml. samples (R1,R2) drawn. A solution (P) of 2.45 μg. I in H2O was prepared by suitable dilutions Samples O1, D, R1, and P were treated with 5 ml. alc., followed after mixing by 0.5 ml. Ehrlich reagent. Samples O2 and R2 received 0.5 ml. of 1:1 alc.-acid. The solutions were kept 1-2 hrs. at room temperature Solutions O2 and R2 showed no significant difference from B when examined at 530 and 540 mμ. Solutions O1, D, R1 and P were measured with O2 as control. The following results were obtained (λ in mμ, optical density of O1, D, R1, and P given): 500, 0.089, 0.051, 0.038, 0.144; 510, 0.120, 0.070, 0.050, 0.203; 520, 0.154, 0.098, 0.060, 0.269; 530, 0.179, 0.121, 0.056, 0.323; 535, 0.183, 0.132, 0.050, -; 540, 0.186, 0.139, 0.040, 0.375; 544, -, 0.141, -, 0.386; 545, 0.185, 0.141, 0.030, 0.386; 550, 0.176, 0.138, 0.025, 0.377; 560, 0.125, 0.100, 0.020, 0.287. Two solutions of II (200 μg. and 10 μg.) in H2O were treated with alc. and Ehrlich reagent. After 1 hr. the stronger solution was pale pink and after 1 week it had become deep purple and the weaker one was pale pink. HC(OEt)3 (90 ml.) and 35 g. Mg heated at 60°, 2 ml. IV added, followed by a little MeI, cooling being required to keep the temperature below 70°, 49.5 ml. more IV added at such a rate as to maintain a temperature of 60°, next day the flask cooled, saturated NH4Cl added dropwise until the mixture became solid, the cake collected, and the filtrate evaporated gave 45 g. 3-methyl-3-butenal diethyl acetal (VII), b18-19 58-60°, b745 162°, n21D 1.4155. VII (13.2 g.) in 20 ml. Et2O treated gradually with 85 ml. ethereal M perphthalic acid, allowed to warm, and kept below 30° by occasional cooling, the next day the phthalic acid removed, and the filtrate extracted with aqueous NaHCO3 gave 10.9 g. 3,4-epoxy-3-methylbutanal diethyl acetal (VIII), b17 83-4°. VIII (3 g.) and 20 ml. MeOHNH3 kept 24 hrs. at 37° and distilled gave 1.95 g. 4-amino-3-hydroxy-3-methylbutanal diethyl acetal (IX), b17 130°, purple color with Ehrlich reagent. Aqueous NH3, either at 100° for 3.5 hrs., or at room temperature 48 hrs. also opened the epoxide ring; the best yield of IX was 65%. IX (1.5 g.) distilled with a solution of 4.5 g. citric acid in 400 ml. H2O until the Ehrlich test became weak and III was isolated from the distillate as for I, giving 200 mg. III, b. 142-3°, darkened rapidly in the air. III (38%) was obtained by dissolving IX in H2O and 3 g. citric acid and distilling the whole in stream until 400 ml. distillate had collected; a Hg complex of III was formed when IV was kept 2 days at 40° with 450 mg. NH4OAc, 2.5 ml. 0.5N AcOH, and 900 mg. HgCl2 with occasional shaking. The following general procedure for preparing benzopyrrocolinediones was developed. The pyrrole (x g.) and 10x g. V mixed with 15x g. AcOH in a tube and when sealed heated 2 hrs. at 180-90°, the product refluxed with H2O, the black residue extracted with hot alc., the alc. filtrate taken to dryness, the residue treated with C6H6, filtered, and the filtrate after concentration chromatographed on Al2O3 gave the crystalline benzopyrrocolinedione. I (600 mg.) gave 98 mg. 3-methylbenzo[f]pyrrocoline-5,10-dione, needles, m. 173-4° (ligroine), ν 1708 and 1655 cm.-1. A mixture of 1- and 2-methylbenzo[f]pyrrocoline-5,10-diones (57 mg.) was obtained from 200 mg. III. Recrystallization from alc. gave 18 mg. of one isomer, m. 223°. The mother liquors and washings from the 1st recrystallization evaporated and the residue crystallized gave 13 mg. of the other isomer, m. 169-70°. Both isomerides showed ν 1708 and 1655 cm.-1 in KCl. 2-Ethylpyrrole (364 mg.) gave 43 mg. 1-ethylbenzo[f]pyrrocoline-5,10-dione, m. 114°, after sublimation in vacuo and crystallization from MeOH. Condensation of 2,4-dimethylpyrrylmagnesium bromide [from 6.4 g. 2,4-dimethylpyrrole (IXa)] and 5 g. V in Et2O gave a solid by filtration after decomposition of the mixture with ice and CO2; the aqueous filtrate extracted with Et2O and acidified and the precipitates combined and crystallized gave 7.2 g. 2-(ο-carboxybenzoyl)-3,5-dimethylpyrrole (X), m. 195-6.5° (decomposition) (MeOH-H2O). X on warming with Ehrlich reagent developed a cherry red color. X (100 mg.) refluxed 1.5 hrs. with 2 ml. H2O and 5 drops NH4OH gave 27.5 mg. 1,3-dimethylbenzo[f]pyrrocoline-5,10-dione (XI), m. 181-3° (alc.), ν 1705, 1650 cm.-1 KCl, λ 378, 318, 267, 237 mμ, log ε 3.67, 3.71, 4.28, and 4.42, resp. XI was also obtained on heating IXa and V by the standard procedure. XI (52.5 mg.) heated 1 hr. with 2 ml. 2N NaOH gave X.
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Reference:
Synthesis and Crystal Structure of a Chiral C3-Symmetric Oxygen Tripodal Ligand and Its Applications to Asymmetric Catalysis,
Chiral lanthanide(III) complexes of sulphur–nitrogen–oxygen ligand derived from aminothiourea and sodium D-camphor-β-sulfonate