Synthesis of 6-substituted thieno[3,2-b]pyrroles. Analogs of tryptophan, tryptamine, and indoleacetic acid

Diels–Alder/Ene Reactivities of 2-(1′-Cycloalkenyl)thiophenes and 2-(1′-Cycloalkenyl)benzo[b]thiophenes with N-Phenylmaleimides: Role of Cycloalkene Ring Size on Benzothiophene and Dibenzothiophene Product Distributions

“…Method I: The Preparation of Thienyl Alcohols 14(i−v) and 15(i−v). Thiophene (11) or Benzothiophene (12) (5.0 g, 59.4 mmol) was placed in a 100 mL, three-neck, round-bottom flask fixed with a condenser. The flask was flushed with nitrogen for 10 min and placed in a dry ice/acetone bath.…”

“…Polycyclic thiophene and benzothiophene-based heterocycles are key intermediates and relevant targets in the fields of synthetic, medicinal, and materials chemistry. − In modern drug discovery, polysubstituted thiophenes are important because they constitute a bioisosteric replacement for the phenyl ring. Thiophene-containing derivatives are often characterized by reduced toxicity and better pharmacokinetic properties .…”

Synthesis of Heterocyclic Compounds Possessing the 4H-Thieno[3,2-b]Pyrrole Moiety

“…38 Some of the mentioned esters were then hydrolyzed to the corresponding acids, which usually served as convenient starting materials in subsequent transformations, for example, for synthesis of the corresponding amides 13,18 or decarboxylated products. 18 Syntheses of several annulated heterocycles possessing the 4H-thieno [3,2-b]pyrrole moiety have been previously described, for example, thieno [2,3-b]indolizine IV, 39 5,6,7,8tetrahydro-4H-thieno[3′,2′:2,3]pyrrolo [4,5-c]pyridine V, 14 8-oxo-5,6,7,8-tetrahydrothieno[2′,3′:4,5]pyrrolo [1,2-a]pyrazine VI, 38 3H,4H,5H-thieno[3′,2′:2,3]pyridazin-4-ones VII, 11,37 and 5-oxo-6,11-dihydro-5H-benzo[e]thieno[2′,3′:4,5]pyrrolo-[1,2-a] 1,4 diazepine VIII. 34 Among the synthesized compounds containing the thieno [3,2-b]pyrrole moiety, several physiologically active agents were described.…”

“…The parent heterocycle I was synthesized in 1957 by the reductive cyclization of 3-nitro-2-thienylpyruvic acid, followed by decarboxylation of the product, namely, thieno[3,2- b ]pyrrole-5-carboxylic acid, and also by the reduction of 2 H ,3 H -thieno[3,2- b ]pyrrol-3-one obtained via cyclization of pyrrole-3-thioacetic acid . The general synthetic approach to the substituted alkyl thieno[3,2- b ]pyrrole-5-carboxylates includes transformation of compounds II into numerous derivatives III under treatment of different reagents. − For example, the reported works describe synthesis of alkyl thieno[3,2- b ]pyrrole-5-carboxylates III with the following substituents: 2-formyl, , 2-acetyl, 2-bromo, 2,6-dibromo, 2,3,6-tribromo, 2-nitro, 2,6-dinitro, 3-formyl, 4-benzyl, 4-(2-nitrobenzyl), , 6-dimethylaminomethyl, 6-(1-piperidinylmethyl), 6-cyanomethyl, 6-formyl, , 2-methyl-3-acyl, − 2-methyl-3,6-diacyl, , 2-methyl-4-(2-oxopropyl), and 2-methyl-4-(2-oxo-2-phenylethyl) . Some of the mentioned esters were then hydrolyzed to the corresponding acids, which usually served as convenient starting materials in subsequent tran...…”

“…Syntheses of several annulated heterocycles possessing the 4 H -thieno[3,2- b ]pyrrole moiety have been previously described, for example, thieno[2,3- b ]indolizine IV , 5,6,7,8-tetrahydro-4 H -thieno[3‘,2‘:2,3]pyrrolo[4,5- c ]pyridine V , 8-oxo-5,6,7,8-tetrahydrothieno[2‘,3‘:4,5]pyrrolo[1,2- a ]pyrazine VI , 3 H ,4 H ,5 H -thieno[3‘,2‘:2,3]pyridazin-4-ones VII , , and 5-oxo-6,11-dihydro-5 H -benzo[e]thieno[2‘,3‘:4,5]pyrrolo[1,2- a ] 1,4 diazepine VIII . Among the synthesized compounds containing the thieno[3,2- b ]pyrrole moiety, several physiologically active agents were described.…”