2,4-Diarylpyrroles: synthesis, characterization and crystallographic insights
摘要:
Three 2,4-diarylpyrroles were synthesized starting from 4-nitrobutanones and the crystal structures of two derivatives were analysed. These are 4-(4-methoxyphenyl)-2-(thiophen-2-yl)-1H-pyrrole, C15H13NOS, and 3-(4-bromophenyl)-2-nitroso-5-phenyl-1H-pyrrole, C16H11BrN2O. Although pyrroles without substituents at the α-position with respect to the N atom are very air sensitive and tend to polymerize, we succeeded in growing an adequate crystal for X-ray diffraction analysis. Further derivatization using sodium nitrite afforded a nitrosyl pyrrole derivative, which crystallized in the triclinic space group P\overline{1} with Z = 6. Thus, herein we report the first crystal structure of a nitrosyl pyrrole. Interestingly, the co-operative hydrogen bonds in this NO-substituted pyrrole lead to a trimeric structure with bifurcated halogen bonds at the ends, forming a two-dimensional (2D) layer with interstitial voids having a radius of 5 Å, similar to some reported macrocyclic porphyrins.
A Modular Synthesis of Unsymmetrical Tetraarylazadipyrromethenes
摘要:
A stepwise route to unsymmetrical tetraarylazadipyrromethenes by a condensation of 2,4-diaryl-5-nitroso-pyrroles with 2,4-diarylpyrroles is described. This modular building-block approach allows for the introduction of up to four different aryl substituents on the azadipyrromethene and is tolerant of a varied substituent set. An efficient synthesis of the 2,4-diarylpyrroles building blocks from 1,3-diaryl-4-nitro-butan-1-ones by nitro hydrolysis to a keto-aldehyde and subsequent ammonia condensation reaction has been achieved. The facile conversion of 2,4-diarylpyrroles into their alpha-nitroso analogues by their reaction with sodium nitrite generated the second building block required for the synthesis.
Base-promoted ring-closing carbonyl–allene metathesis for the synthesis of 2,4-disubstituted pyrroles
作者:Guolin Cheng、Weiwei Lv、Lulu Xue
DOI:10.1039/c8gc01675e
日期:——
A base-promoted ring-closing carbonyl–allene metathesis reaction of N-allenyl β-enaminones (generated in situ from N-propargyl β-enaminones) gives 2,4-disubstituted pyrroles with cleavage of the C(sp)–C(sp3) bond. This transition metal-free procedure generates 1 equiv. of acetic acid as the sole byproduct. A preliminary mechanistic study supports a stepwise [2 + 2] cycloaddition/retro [2 + 2] reaction
Reaction between 4-Nitro-1,3-diarylbutan-1-ones and Ammonium Acetate in the Presence of Morpholine and Sulfur: An Efficient Synthesis of 2,4-Diarylpyrroles
An efficient synthesis of 2,4-diarylpyrroles is described. Heating a mixture of a 4-nitro-1,3-diarylbutan-1-one and ammoniumacetate in the presence of morpholine and sulfur afforded the corresponding 2,4-diarylpyrroles in excellent yields.
Synthesis of π-conjugated asymmetric aza-BODIPYs via nitrosobicyclopyrroles
作者:Ryota Mori、Minenari Asakura、Yukinori Kobayashi、Hiromu Mashimo、Makoto Roppongi、Satoshi Ito
DOI:10.1016/j.tetlet.2022.153759
日期:2022.4
π-Conjugated aza-BODIPYs with absorption in the near-infrared region have attracted attention, but there are few reports of their synthesis. We report the synthesis and absorption properties of π-conjugated asymmetricaza-BODIPYs by nitrosation and retro-Diels-Alder reaction of bicyclo[2.2.2]octadiene-fused bicyclopyrroles. We also synthesized aza-BODIPY fused with [2.3]naphtho and [2.3]anthra structures