An Intramolecularly Hydrogen Bonded Dihydrotripyrrinone
摘要:
A yellow tripyrrole analog (1) of bilirubin has been synthesized, and its lone propionic acid group is found to engage in conformation determining, intramolecular hydrogen bonding in solution and in the crystal. Molecular modelling and X-ray crystallography reveal an abbreviated ridge-tile or L-shape conformation in which an essentially planar dipyninone is hydrogen bonded to the single opposing propionic acid group. In the (arbitrary) (P)-helicity ridge-tile, the torsion angles about C(10) are computed to be 55 degrees and 61 degrees by molecular dynamics and found to be 66 degrees and 53 degrees in the crystal. Such torsion angles lead to an interplanar dihedral angle (similar to 93 degrees) between the dipyninone and its adjoining pyrrole that is very close to the dihedral angle (similar to 98 degrees) found in intramolecularly hydrogen bonded bilirubin.
A general synthesis of 5-unsubstitutedbenzylpyrrole-2-carboxylates was developed based on the reaction of β-nitroacetates with benzylisocyanoacetate. The advantage of this route over other pyrrole syntheses was the regiochemical control of the substitution pattern on the pyrrole ring.
Regiocontrolled Synthesis of Pyrrole-2-carboxaldehydes and 3-Pyrrolin-2-ones from Pyrrole Weinreb Amides
作者:Aaron R. Coffin、Michael A. Roussell、Elina Tserlin、Erin T. Pelkey
DOI:10.1021/jo061043m
日期:2006.8.1
A regiocontrolledsynthesis of 3,4-disubstituted pyrrole-2-carboxaldehydes was completed in two steps from acyclic starting materials. A Barton−Zard pyrrolesynthesis between N-methoxy-N-methyl-2-isocyanoacetamide and α-nitroalkenes or β-nitroacetates provided N-methoxy-N-methyl pyrrole-2-carboxamides (pyrrole Weinreb amides), which were converted into the corresponding pyrrole-2-carboxaldehydes by
A new methodology for the preparation of 2-cyanopyrroles and synthesis of porphobilinogen
作者:Maciej Adamczyk、Rajarathnam E. Reddy
DOI:10.1016/0040-4020(96)00941-6
日期:1996.11
Condensation of α-acetoxynitro compounds 4a-f with isocyanoacetonitrile (5) using DBU in THF afforded 2-cyano-3,4-substituted pyrroles 6a-f, in good yield. Porphobilinogen (PBG, 12), the key building block for the preparation of tetrapyrrolic natural products, was synthesized from 2-cyano-3,4-substituted pyrrole 6f, in four steps.
作者:Timothy D. Lash、John R. Bellettini、Jolie A. Bastian、Kendall B. Couch
DOI:10.1055/s-1994-25431
日期:——
Benzyl esters of 5-unsubstituted pyrrole-2-carboxylic acids were prepared in excellent yields by the base-catalyzed condensation of benzyl isocyanoacetate with α-acetoxynitro compounds, or nitroalkenes,in refluxing tetrahydrofuran. These pyrrolic products are important intermediates in the synthesis of porphyrins and related compounds.
The Synthesis of 1,2,3-Triazoles from Nitroalkenes - Revisited
作者:Béatrice Quiclet-Sire、Samir Z. Zard
DOI:10.1055/s-2005-918463
日期:——
Nitroalkenes or vicinal acetoxy nitro derivatives undergo a clean reaction with sodium azide in hot dimethyl sulfoxide to give the corresponding 1,2,3-triazoles in good yield.