N-Boc-α-diazo glutarimide as efficient reagent for assembling N-heterocycle-glutarimide diads via Rh(II)-catalyzed N–H insertion reaction

• Grigory Kantin,
• Pavel Golubev,
• Alexander Sapegin,
• Alexander Bunev and
• Dmitry Dar’in

Beilstein J. Org. Chem. 2023, 19, 1841–1848, doi:10.3762/bjoc.19.136

• product 6b in high yield. The reaction with methyl pyrrole-2-carboxylate resulted in the isolation of only the C–H insertion product 9c in low yield. Similar reaction progress was observed in the case with imidazole, the product N–H insertion was observed only in trace amounts (according to NMR data of

Nucleophilic and electrophilic cyclization of N-alkyne-substituted pyrrole derivatives: Synthesis of pyrrolopyrazinone, pyrrolotriazinone, and pyrrolooxazinone moieties

• Işıl Yenice,
• Sinan Basceken and
• Metin Balci

Beilstein J. Org. Chem. 2017, 13, 825–834, doi:10.3762/bjoc.13.83

• . Methyl 1-(phenylethynyl)-1H-pyrrole-2-carboxylate (7c) was treated with hydrazine monohydrate in MeOH under N2 atmosphere at reflux temperature. Pyrrolopyrazinone 12c and pyrrolotriazinone 13c skeletons were formed in 67% and 24% yields, respectively (Scheme 2). The structures of cyclization products 12c

• -pyrrole-2-carboxylate derivatives 7b–d were treated with iodine in dichloromethane to yield the corresponding pyrrolooxazinone derivatives 19b–d in yields of 76–79% (Scheme 5). Spectral data of 19b–d were in complete agreement with the proposed structures. The structure of 19c was further confirmed by

• reported here can be used for the introduction of further substituents at various positions of the target structures. Experimental General procedure for N-alkyne-substituted methyl 1H-pyrrole-2-carboxylate derivatives 7a–d. To a solution of bromoalkyne derivatives 11 (1.1 equiv) in freshly distilled

Fe(II)/Et₃N-Relay-catalyzed domino reaction of isoxazoles with imidazolium salts in the synthesis of methyl 4-imidazolylpyrrole-2-carboxylates, its ylide and betaine derivatives

• Ekaterina E. Galenko,
• Olesya A. Tomashenko,
• Alexander F. Khlebnikov,
• Mikhail S. Novikov and
• Taras L. Panikorovskii

Beilstein J. Org. Chem. 2015, 11, 1732–1740, doi:10.3762/bjoc.11.189

• reaction with sulfur affording the corresponding imidazolethiones under very mild conditions. Keywords: imidazole; isoxazole; NHC carbene; pyrrole-2-carboxylate; relay catalysis; Introduction Pyrrole-2-carboxyate and imidazole units are present in bioactive pyrrole-imidazole alkaloids and pyrrole

• hydrolyzing the ester group. Ylides 2 can also be debenzylated, affording the corresponding pyrrolyl imidazoles 12. Thus, ylide 2h was debenzylated on Pd/C with hydrogen to produce methyl 5-(4-fluorophenyl)-4-(1H-imidazol-1-yl)-3-phenyl-1H-pyrrole-2-carboxylate (12d) in quantitive yield. As mentioned above

• mixture was filtered to remove Pd/C, MeOH was evaporated under reduced pressure, water was added to the residue and the product was filtered, washed with water and dried to give the analytically pure compound. Methyl 4-(1H-imidazol-1-yl)-3,5-diphenyl-1H-pyrrole-2-carboxylate (12a): colorless solid, mp 239

Streptopyridines, volatile pyridine alkaloids produced by Streptomyces sp. FORM5

• Ulrike Groenhagen,
• Michael Maczka,
• Jeroen S. Dickschat and
• Stefan Schulz

Beilstein J. Org. Chem. 2014, 10, 1421–1432, doi:10.3762/bjoc.10.146

• [2] such as methyl pyrrole-2-carboxylate, emitted by Stackebrandtia nassauensis, or 2-acetylpyrrole from Saccharopolyspora erythraea, volatile alkaloids are rarely produced by actinomycetes. We became interested in the strain Streptomyces sp. FORM5 to elucidate whether volatile formation is linked to

An organocatalytic route to 2-heteroarylmethylene decorated N-arylpyrroles

• Alexandre Jean,
• Jérôme Blanchet,
• Jacques Rouden,
• Jacques Maddaluno and
• Michaël De Paolis

Beilstein J. Org. Chem. 2013, 9, 1480–1486, doi:10.3762/bjoc.9.168

• -iodoxybenzoic acid) was prepared according to standard procedures. Ethyl 3-(3-methoxy-3-oxopropyl)-1-(4-methoxyphenyl)-5-(pyridin-2-ylmethyl)-1H-pyrrole-2-carboxylate (5a): Representative procedure: In a flask containing a stirred solution of 4a (432 mg, 1.02 mmol, 1.0 equiv) in CH2Cl2 (10.2 mL) at room

• (ESI+): (M + H)+ calcd for C24H27N2O5, 423.1920; found, 423.1926; Rf 0.15 (CH2Cl2/MeOH 99:1). Ethyl 5-(hydroxy(pyridin-2-yl)methyl)-3-(3-methoxy-3-oxopropyl)-1-(4-methoxyphenyl)-1H-pyrrole-2-carboxylate (9a): Representative procedure: In a flask containing a well stirred solution of CAN (269 mg, 0.490

• -pyrrole-2-carboxylate (10a): A solution of 9a (26 mg, 0.0593 mmol) in AcOEt (0.6 mL) was treated with IBX (50 mg, 0.178 mmol, 3 equiv). The suspension was stirred at 80 °C for 4 h before being brought to rt and filtered. Evaporation of the volatile led to analytically pure 10a which can be further

Self-association of an indole based guanidinium-carboxylate-zwitterion: formation of stable dimers in solution and the solid state

• Carolin Rether,
• Wilhelm Sicking,
• Roland Boese and
• Carsten Schmuck

Beilstein J. Org. Chem. 2010, 6, No. 3, doi:10.3762/bjoc.6.3

• factor leading to the overall reduced stability of dimer 2·2. Conclusion In conclusion, we have presented the synthesis of a new indole based zwitterion 2, a close analogue of the 5-(guanidiniocarbonyl)-1H-pyrrole-2-carboxylate (1) which we recently introduced as one of the most stable self-complementary