Glyoxal als Synthon, III Eine einfache Synthese von Aminopyrrolen und Dihydropyrrolo[3,2‐b]pyrrolen

Abstract

The alcoholysis of diazasilacyclopentenes 2, easily obtained from glyoxaldiimines 1 with alkali metal and dichlorosilanes, gives either 3-amino-substituted pyrroles 4 or, with only small amounts of alcohol, N-substituted dihydropyrrolo[3,2-b]pyrroles 5. Reduction of 1 with hydrogen in ethanol in the presence of small amounts of a Pd/C catalyst also gives 4 and 5, together with smaller quantities of a 3,4diaminopyrrole 7. With more of the catalyst the formation of the 1,2-diaminoethanes 6 predominates. A single-crystal X-ray diffraction study was performed for the N,N'-di-tert-butyl derivative 5a, which confirms the expected centrosymmetric structure.

Synthesis and Optical Properties of Tetraaryl‐1,4‐dihydropyrrolo[3,2‐b]pyrroles

“…[10,11] Not surprisingly, various electrophilic aromatic substitutions were introduced, including by the Vilsmeier reaction. Yet another method was developed by Dieck et al in 1989. [12] Interestingly, compounds that have this core were identified by virtual screening as potent inhibitors of human microsomal prostaglandin synthase.…”

1,4‐Dihydropyrrolo[3,2‐b]pyrrole and Its π‐Expanded Analogues

“…Oxidation of 2-b]pirole i ich prozszerzone pochodne przez długi czas pozostawały w cieniu swoich analogów zawierają cych siarkę. [10] In this case, 1,4-diaza-1,3-diene 25 was a substrate in the synthesis of 1,4-dihydropyrroloA C H T U N G T R E N N U N G [3,2-b]pyr-role 29 (Scheme 7). Metody otrzymywania tych związków są wyczerpują co przedstawione i krytycznie porównane.…”

“…Jednak ich zalety w powią zaniu z nowymi metodami syntezy powodują renesans zainteresowania nimi. [10] Compound 25, in reaction with lithium, undergoes reduction followed by condensation with dichlorodimethylsilane, which leads to diazasilylocyclopentene 26. Omówiona jest również ich reaktywność oraz właściwości fizykochemiczne, ze szczególnym uwzglę dnieniem właściwości optycznych.…”

“…This methodology has been patented by Sumitomo Chemical Co. [9] In 1989, Fendesak and co-workers described a completely different approach. [10] In this case, 1,4-diaza-1,3-diene 25 was a substrate in the synthesis of 1,…”

“…. [10] Compound 25, in reaction with lithium, undergoes reduction followed by condensation with dichlorodimethylsilane, which leads to diazasilylocyclopentene 26. Dissolution of 26 in EtOH induced breaking of N À Si bonds, which led to the formation of 27 as two tautomeric forms.…”