Pyrrole studies.

Chiral molecules containing the pyrrole framework

“…[172][173][174] The preparation of 2,2 0 -bipyrroles starting from 2-formyl pyrroles 231 was reported where a formyl pyrrole was converted into a diketone derivative 232 using a,b-unsaturated ketones in the presence of triethylamine and a 1,3-thiazolium salt. 175 The dicarbonyl intermediate 232 was then reacted with amines to give the racemic 2,2 0 -bipyrrole derivatives 233 (Fig. 54).…”

A catalyst-controlled selective synthesis of pyridines and pyrroles

“…30 Encouraged by these results, we became interested in the reactivity of 1,3-dienyl nitrenes as a platform for N-heterocycle synthesis, which could be readily accessible from a-diazo oxime ethers via in situ formation of 2H-azirines. These nitrene intermediates could potentially participate in two alternative pathways: (a) 4p-electrocyclization, 24,31 or (b) 6p-electrocyclization via a 1,6-hydride shi or prototropic isomerization. However, the strong propensity of 1,3-dienyl nitrenes for 4p-electrocyclization to give pyrroles intrigued us as to whether the modulation of the reactivity of nitrenes with an optimal transition metal catalyst would lead to an alteration of their chemoselectivity towards 6p-electrocyclization to provide pyridines.…”

Lewis Acid-Catalyzed One-Pot, Three-Component Route to Chiral 3,3‘-Bipyrroles

“…The commonly encountered bipyrroles possess mainly the 2,2‘-bipyrrole basic moiety. Hinz et al have synthesized 2,2‘-bipyrrole using pyrolysis of 2-azido-5-(2-pyrrolyl)penta-2,4-dienoic esters. Apart from 2,2‘-bipyrrole, Zaitsev et al have also prepared 2,3‘-analogues of bipyrrole through the intermediacy of O -vinyloxime pyrroles.…”