- Stereoselective synthesis of acortatarins A and B
-
Acortatarins A and B have been synthesized via stereoselective spirocyclizations of glycals. Mercury-mediated spirocyclization of a pyrrole monoalcohol side chain leads to acortatarin A. Glycal epoxidation and reductive spirocyclization of a pyrrole dialdehyde side chain leads to acortatarin B. Acid equilibration and crystallographic analysis indicate that acortatarin B is a contrathermodynamic spiroketal with distinct ring conformations compared to acortatarin A.
- Wurst, Jacqueline M.,Verano, Alyssa L.,Tan, Derek S.
-
-
Read Online
- Synthesis and Structure of 2,5-Bis[N-(2,6-mesityl)iminomethyl]pyrrolylcobalt(II): Evidence for One-Electron-Oxidized, Redox Noninnocent Ligand Behavior
-
The title complex Co(Mes2pyr)Cl2 is prepared from CoCl2 and (Mes2pyr)H. Instead of the expected (Mes2pyr)CoCl complex, a complex with formula (Mes2pyr)CoCl2 is isolated wherein the angle strain of the Mes2pyr ligand results in metal ligation by only two of the three ligand donor atoms. Careful examination of structural, spectroscopic, and magnetic features indicates this compound is best described as a complex of high-spin Co(II) with a neutral radical ligand.
- Peters, Garvin M.,Winegrad, Jacob B.,Gau, Michael R.,Imler, Gregory H.,Xu, Beibei,Ren, Shenqiang,Wayland, Bradford B.,Zdilla, Michael J.
-
-
Read Online
- Absorption and fluorescence properties of chalcones having pyrrole or indole moiety
-
2′-Hydroxychalcone derivatives having pyrrole ring have been synthesized and their absorption and fluorescence properties have been examined in connection to intramolecular hydrogen bonding.
- Arai, Tatsuo
-
-
Read Online
- Double intramolecular hydrogen transfer assisted dual emission in a carbazole-embedded porphyrin-like macrocycle
-
The introduction of a pyrrole ring at one of themesopositions of carbazole-based porphyrins lowers the structural symmetry and results in dual emission, which strongly depends on the excitation wavelength and temperature. The origin of dual emission induced by NH-tautomerism is confirmedviaphotophysical and DFT calculations.
- Kalaiselvan, Arumugan,Spergen, Aswini,Krishna, Isukapalli Sai Vamsi,Reddy, Vennapusa Sivaranjana,Gokulnath, Sabapathi
-
supporting information
p. 4420 - 4423
(2021/05/10)
-
- Carbohydrate receptors combining both a macrocyclic building block and flexible side arms as recognition units: Design, syntheses, and binding studies
-
Carbohydrate receptors combining a macrocyclic building block and two flexible side arms were designed on the base of the analysis of the binding motifs found in the crystal structures of the complexes formed between artificial receptors and monosaccharides, reported previously by our group. Binding studies in two-phase systems, such as extractions of sugars from water into organic phase, as well as in homogeneous organic media, using 1H NMR and fluorescence spectroscopic titrations, confirmed the suitability of the designed compounds to act as highly effective and selective carbohydrate receptors. Depending on the nature of the bridges and side arms used as the building blocks, various receptors with different binding properties could be developed. The obtained results confirmed the validity of the receptor design and revealed that crystalline receptor-sugar complexes are particularly a valuable basis for the design of new effective receptor systems.
- Lippe, Jan,Mazik, Monika
-
p. 1427 - 1439
(2015/02/19)
-
- Total synthesis and stereochemical revision of acortatarins A and B
-
A first total synthesis of acortatarins A, B, and an enantiomer of the proposed structure of acortatarin B is described by using readily available d-sugars. This convergent total synthesis revealed the revision of the absolute configuration of acortatarin A and structural revision of acortatarin B. The key steps involved are regioselective epoxide opening with deprotonated 2,5-disubstituted pyrrole and spiroketalization.
- Sudhakar, Gangarajula,Kadam, Vilas D.,Bayya, Shruthi,Pranitha, Gavinolla,Jagadeesh, Bharatam
-
supporting information; experimental part
p. 5452 - 5455
(2011/12/05)
-
- Oxidation of 2,5-dialkylpyrrole derivatives with cerium(IV) ammonium nitrate
-
A new four-step procedure for the synthesis of 2,5-diformylpyrrole from hexane-2,5-dione was developed. The oxidation reaction of substituted 2,5-dialkylpyrroles with cerium(IV) ammonium nitrate (CAN) has been studied in detail. It was found that the outc
- Voloshchuk, Roman,Galezowski, Michal,Gryko, Daniel T.
-
experimental part
p. 1147 - 1152
(2009/12/04)
-
- Pincer ligands based on α-amino acids: I. Synthesis of polydentate ligands from pyrrole-2,5-dicarbaldehyde
-
New chiral pincer ligands having CH=N moieties were synthesized by condensation of 1H-pyrrole-2,5-dicarbaldehyde with l-methionine and l-histidine methyl esters. Their reduction under mild conditions (NaBH4, -30°C) gave the corresponding amine ligands in high yields. An improved procedure for the preparation of 1H-pyrrole-2,5-dicarbaldehyde was proposed.
- Knizhnikov,Borisova,Yurashevich,Popova,Chernyad'ev,Zubreichuk,Reshetova
-
p. 855 - 860
(2008/02/10)
-
- Novel aromatic compounds and poly(oxyalkylene) containing aromatic compounds possessing antibacterial, antifungal or antitumor activity
-
The present invention provides novel compounds possessing one or more of the following activities: antibacterial, antifungal and antitumor activity. The compounds are of Formula (I): Pharmaceutical compositions containing these compounds, methods of making and methods for using these compounds are also provided.
- -
-
-
- Novel compounds possessing antibacterial, antifungal or antitumor activity
-
The present invention provides novel compounds possessing one or more of the following activities: antibacterial, antifungal and antitumor activity. The compounds are of Formula (I): Pharmaceutical compositions containing these compounds, methods of making and methods for using these compounds are also provided.
- -
-
-
- Synthesis of 5-substituted pyrrole-2-carboxaldehydes. Part I. Generation of formal 5-lithiopyrrole-2-carboxaldehyde equivalents by bromine-lithium exchange of 2-bromo-6-(diisopropylamino)-1-azafulvene derivatives
-
The first known lithiated 1-azafulvene derivatives, e.g., 8 and 13a, were generated by a low-temperature bromine-lithium exchange procedure with tert-butyllithium.These lithio species show substantial stability at /=-90 deg C because, at these temperatures, the sterically demanding 6-diisopropylamino moiety, unlike the dimethylamino group, completely inhibits nucleophilic addition to C-6.At higher temperatures, the addition of tert-butyllithium to C-6 is significant and it can become the dominant process.The lithio species 8 is a useful formal equivalent of 5-lithiopyrrole-2-carboxaldehyde since, on reaction with electrophilic reagents and subsequent hydrolysis, a wide variety of regiochemically pure 5-substituted pyrrole-2-carboxaldehydes is formed.The 6-dialkylamino-1-azafulvenes described herein exist predominantly or exclusively as the syn conformer in solution at room temperature.This conformational preference is confirmed by a significance NOE effect between H-4 and H-6 in the parent diisopropylamino compound 3f.The origin of the syn conformational preference stems from a substantial contribution of the charge-separated form 16 to the ground state structure of these compounds, a phenomenon that is strongly supported by variable temperature NMR measurements on 2-bromo-6-diisopropylamino-1-azafulvene (3c).Key words: 2-bromo-6-diisopropylamino-1-azafulvenes, stereochemistry, lithiation, pyrolle-2-carboxaldehydes.
- Berthiaume, Sylvie L.,Bray, Brian L.,Hess, Petr,Liu, Yanzhou,Maddox, Michael L.,et al.
-
p. 675 - 684
(2007/10/02)
-
- A Convenient General Method for the Synthesis of Pyrrole-2,5-dicarbaldehydes
-
A new general method for the synthesis of pyrrole-2,5-dicarbaldehyde and its 3-mono- and 3,4-disubstituted derivatives is reported.It involves the intermediate formation of the corresponding 2,5-bis(1,3-benzodithiol-2-yl)pyrroles followed by hydrolysis with HgO-35percent aq.HBF4-DMSO.Pyrrole-2,5-dicarbaldehyde was obtained in overall yields of 43-65percent, whilst that of the derivatives was 32-90percent.Moreover the methylation of the corresponding dithiolic intermediate with further hydrolysis resulted in the formation of 1-methylpyrrole-2,5-dicarbaldehyde in 90percent overall yield.
- Cadamuro, Silvano,Degani, Iacopo,Fochi, Rita,Gatti, Antonella,Piscopo, Laura
-
p. 2939 - 2944
(2007/10/02)
-
- 216. Lithiated Azafulvenes by Halogen/Metal Interchange of Brominated 6-(Diisopropylamino)-1-azafulvene Derivatives. Novel Synthesis of 5-Mono- and 4,5-Disubstituted 1H-Pyrrole-2-carbaldehydes
-
The first known lithiated 1-azafulvene derivatives were generated by low-temperature halogen/metal interchange, with t-BuLi, from the corresponding brominated 6-diisopropylamino compounds 3b and 12.These Li species reacted with sundry electrophilic reagents to give products which, on the basic hydrolysis, were converted into 5-mono- or 4,5-disubstituted pyrrole-2-carbaldehydes 10 and 16, respectively.
- Bray, Brian L.,Hess, Petr,Muchowski, Joseph M.,Scheller, Markus E.
-
p. 2053 - 2057
(2007/10/02)
-
- LITHIATION OF THE 6-DIMETHYLAMINO-1-AZAFULVENE DIMER. A VERSATILE SYNTHESIS OF 5-SUBSTITUTED PYRROLE-2-CARBOXALDEHYDES.
-
Metalation of the dimer 1 of 6-dimethylamino-1-azafulvene, with t-butyllithium at -15 deg C, gave the 3,8-dilithio derivate 2, which after reaction with diverse electrophilic reagents and hydrolysis, provided a wide variety of 5-substituted pyrrole-2-carboxaldehydes 5.
- Muchowski, Joseph M.,Hess, Petr
-
p. 777 - 780
(2007/10/02)
-
- SYNTHESIS OF AROMATIC ALDEHYDES VIA 2-ARYL-N,N'-DIACYL-4-IMIDAZOLINES
-
Diacylimidazolium ions yield adducts with aromatic compounds.Thus the N,N'-diacetylimidazolium ion and indole gives 1,3-diacetyl-2-(3-indolyl)-4-imidazoline.Less reactive substrates such as thiophene, anisole and 1,3-dimethylbenzene fail to react with this reagent but do form adducts (e.g. 1,3-bis-(trifluoroacetyl)-2-(2-thienyl)-4-imidazoline) with an imidazole/trifluoroacetic anhydride reagent.All of the adducts could be converted to the corresponding aldehyde under mild conditions.The synthetic scope of the new synthesis is similar to that of the Vilsmeier-Haack reaction.
- Bergman, Jan,Renstroem, Lars,Sjoeberg, Birger
-
p. 2505 - 2512
(2007/10/02)
-
