The reaction of an aromatic heterocycle with a proton is called a protonation. One of articles about this theory is 《Practical synthesis of thieno[3,2-b]pyrrole》. Authors are Matteson, Donald S.; Snyder, H. S..The article about the compound:3-Methyl-1H-pyrrolecas:616-43-3,SMILESS:CC1=CNC=C1).Application of 616-43-3. Through the article, more information about this compound (cas:616-43-3) is conveyed.
cf. C.A. 51, 16422a. KCNS(200 g.) in 250 ml. MeOH at -75° (Dry Ice-Me2CO bath) stirred with dropwise addition of 159.6 g. Br in 125 ml. MeOH at -75° and the mixture kept below -60°, the thiocyanogen solution cooled to -75° and treated rapidly with 67.1 g. redistilled pyrrole in 250 ml. MeOH at -75° and the mixture stirred (with cooling bath removed) until the temperature rose to -25°, poured onto 2 kg. crushed ice and stirred with 300 g. NaCl, filtered through a 5-6-in. Buchner funnel and the ice and solids washed freely with H2O, the crude 3-thiocyanopyrrole (I) dried in vacuo and clarified in 100 ml. CH2Cl2 and 500 ml. methylcyclohexane (MgSO4 and Darco) at 40°, the colorless solution chilled and seeded, kept 17 hrs. at 0°, and chilled to -20° gave 62 g. I, m. 40-4°, infrared spectrum identical with that of I prepared from Cu(CNS)2 and pyrrole. I stains the skin deep red and may cause burning or itching sensations. The use of rubber gloves is mandatory and contacted areas should be washed immediately with soap and H2O and treated with 3% H2O2. Pyrrole (0.71 g.) in 75 ml. MeOH stirred at 0-5° (N atm.) with portionwise addition of 0.2 mole Cu(CNS)2 [on basis of (NCS)2 analysis] in a few min. and stirring continued 50 min. at 0-5°, the mixture filtered and the CuCNS washed with 50 ml. MeOH, the filtrate and washings poured onto 300 g. crushed ice and 100 g. NaCl added, the mixture filtered and the solids extracted with 225 ml. methylcyclohexane, the solution treated with Darco and cooled, seeded, and kept 17 hrs. at 0° gave 5.83 g. I, m. 41.5-43° (methylcyclohexane). As a route to 3-(alkylthio)pyrroles, attempts to isolate 3-mercaptopyrrole (II), 3-RSC4H4N (R = H) (IIa), were made but abandoned when a more promising way was found. Mg (1.87 g.) in 125 ml. MeOH (N atm.) at -20° kept 1 hr. with 6.2 g. I and the mixture poured into 500 ml. H2O, 200 ml. Et2O, and sufficient solid CO2 to dissolve the precipitated Mg(OH)2, the aqueous phase extracted with Et2O and the dried Et2O solutions evaporated in vacuo, the residue sublimed at 75°/0.1 mm. and the product (6.8 g.) recrystallized from PhMe, resublimed, recrystallized from dilute MeOH, and resublimed at 55-65°/0.1 mm. gave S-3-pyrrolyl O-Me thioimidocarbonate, II [R = C(:NH)OMe], m. 77-80°. I(6.21 g.) and 8.5 g. MeI in 50 ml. MeOH at -20° (N atm.) stirred with dropwise addition in 10 min. of 7.9 g. 85% KOH in 20 ml. H2O and 20 ml. MeOH and stirring continued 1.5 hrs. without cooling, the excess alkali neutralized with solid CO2 and the mixture poured into 500 ml. H2O containing 100 g. NaCl, the mixture extracted 3 times with 50 ml. CH2Cl2 and the dried solution (K2CO3) evaporated in vacuo, the residue distilled, and the product (5.1 g.) redistilled gave II (R = Me) (IIb), b12-13 88-9°. The excellent (90%) yield of IIb showed that the extremely unstable anion of IIa exists long enough to displace halide ions from a moderately active alkyl halide. I (62.1 g.) and 83.5 g. BrCH2CO2H in 500 ml. MeOH at -50° stirred rapidly with addition of 123 g. 85% KOH in 500 ml. 50% dilute MeOH in 10 min. and stirring continued 2 hrs. without cooling, the mixture brought to pH 8 with solid CO2 and the solvent evaporated in vacuo (warm H2O bath to avoid bumping), the solid residue taken up in 500 ml. CH2Cl2 and the mixture stirred with controlled addition of 375 ml. ice-cold 4N HCl, the aqueous phase extracted twice with 250 ml. CH2Cl2 and the combined dried CH2Cl2 solutions treated with Darco and filtered, the filtrate saturated with excess dry NH3, and filtered gave 78 g. II (R = CH2CO2NH4) (IIc), m. 127-33°, purified by treatment of IIc with N HCl and extraction with CH2Cl2, dehydration over MgSO4, and crystallization by treatment with anhydrous NH3 to give IIc, m. 125-33°; Ca salt-2H2O, m. 112-20° (decomposition). IIc in MeOH refluxed 20 hrs. with ZnCl2 and the product purified by extraction followed by distillation in a sublimation apparatus at 80°/0.1 mm. gave the liquid ester II (R = CH2CO2Me). BrCH2CH(OEt)2 failed to react with I under the above conditions and active alkyl halides such as PhCOCH2Br, BrCH2CO2Et, and ClCH2COCO2H appeared to be attacked by OH- more rapidly than was I and also failed to give sulfides. IIc (17.42 g.) and 250 ml. CH2Cl2 shaken with 30 ml. ice-cold 6N HCl and the aqueous phase extracted twice with 250 ml. CH2Cl2, the combined CH2Cl2 extracts dried (MgSO4) and treated with Darco, filtered and the filtrates combined with the 150 ml. CH2Cl2 washings of the Mg2SO4, the CH2Cl2 solution added dropwise in 50 min. to the most vigorously agitated region of 400 g. well-stirred polyphosphoric acid at 120-3° with free vaporization of the CH2Cl2, the mixture cooled below 100° and added slowly with stirring to 1200 ml. H2O and 750 ml. EtOAc, the stirring continued 30 min. and the aqueous layer extracted with 250 ml. EtOAc, the aqueous layer saturated with 300 g. NaCl and extracted twice with 250 ml. EtOAc, the emulsion layer neutralized with Na2CO3 and warmed on a steam bath prior to a 3-fold extraction with 100 ml. portions of EtOAc, the combined EtOAc solutions washed with aqueous NaHCO3 and dried over MgSO4, evaporated in vacuo, and the residue sublimed twice at 120°/0.1 mm. gave 5.0 g. product, m. 183-8.5°, purified by sublimation twice, recrystallization twice from aqueous HCONMe2 and sublimation twice, treatment with Darco, and recrystallization from MeOH to give 2H,3H-thieno[3,2-b]pyrrol-3-one (III), m. 187-90°, λ 330, 303 (min.), 279, 236 (min.) mμ (ε 7400, 3900, 16,000, 500, 95% alc.), ν 3140, 1635 cm.-1 (Nujol). III (0.28 g.) in 35 ml. 95% alc. refluxed 1 hr. with 2.5 g. Raney Ni (W6) and the solution filtered, the residue washed with alc. and the alc. solutions evaporated in vacuo, the residue sublimed, and the product (0.06 g.) recrystallized from H2O gave 23 mg. 2-acetylpyrrole, m. 89-91°, identical with that prepared from C4H4NMgBr and AcCl. III (1.39 g.) and 1.5 g. NaBH4 in 50 ml. MeOH refluxed 16 hrs. under N and the mixture poured into 200 ml. 15% aqueous NaCl, extracted 3 times with 50 ml. CH2Cl2 and the dried extract evaporated, the residue sublimed at 6070°/0.1 mm., and the 0.76 g. product recrystallized from Et2O-C5H12 at -70° and resublimed 3 times gave thieno[3,2-b]pyrrole, m. 25-8°, λ 260, 233 (min.) mμ (ε 11,800, 4900, 95% alc.), infrared spectrum and that of a less pure sample synthesized from thiophene (cf. Snyder, et al., C.A. 51, 13846b) given.
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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