Pyrrole ring synthesis

A new pyrrole ring synthesis developed by Arcadi involves the addition of ammonia or benzylamine to 4-pentynones, the latter of which are conveniently prepared via a palladium oxidative coupling sequence as shown below for the synthesis of 40 [39,40]. 

The second alternative synthesis of stannylpyrroles involves the versatile van Leusen pyrrole ring synthesis, illustrated below for the synthesis of 85 [69,70]. Several examples were prepared in these studies, although at present the scope of this reaction is limited to pyrroles having an electron-withdrawing group at the 3-position. The structure of a BOC derivative of 85 (Ri = Ph, R2 = Bz) was established by X-ray crystallography [69]. 

Yamamoto and co-workers have reported the novel pyrrole ring synthesis shown for 56, involving the Pd-induced union of methyleneaziridines 54 and 2-acetylpyridine (55) [45]. Similar reactions of 3- and 4-acetylpyridine give pyrroles 57 and 58, respectively. 

Zinc sodium acetate Reductive pyrrole ring synthesis... 

Potassium carbonate One-step pyrrole ring synthesis with hydroxylamine-O-sulfonic acid... 

Favorskii rearrangement, iminolactones by - 23, 457 Feist>Benary furan ring synthesis 15, 624 Feist pyrrole ring synthesis, modified 21, 813 Ferrates s. Potassium hexacyanoferrate(III)... 

Feist pyrrole ring synthesis Fischer-type ring closure Pschorr — diketone —... 

This synthesis of the pyrrole ring system, due to Knorr, consists in the condensation of an a-aminoketone with a 1,3-diketone or the ester of a p-keto-acid, a-Aminoketones are unstable in the free state, readily undergoing self-condensation consequently they must be prepared, by the reduction of an a-nitroso (or oximino) ketone, in the presence of the 1,3-diketone or p-ketoester, to ensure rapid interaction. 

The pyrrole ring in numerous natural products has been constructed using a PK synthesis. Examples include lamellarin L, funebrine, magnolamide, and... 

The important biological role of the isobacteriochlorins has decisively influenced the development of synthetic approaches leading to the isobacteriochlorin class of compounds. All of the naturally occurring isobacteriochlorins contain geminally dialkylated structural parts in the saturated pyrrole rings, which require special approaches for their synthesis. Until the discovery of siroheme and sirohydrochlorin, this structural element could only be found in vitamin B,2. Using the synthetic potential, which was invented during numerous syntheses of... 

Oxidation reactions were used in the synthesis of porphyrin d, the metal-free ligand system of naturally occurring heme d,. In a total synthesis of porphyrin d,12d oxo functions were introduced into isobacteriochlorin 3 by selenium dioxide oxidation to yield 4. The selenium dioxide selectively attacks the 3- and 8-positions of the partially reduced pyrrole rings of the chromophore. In another synthesis23a c of porphyrin d, an isobacteriochlorin 5, derived by... 

The synthesis is straightforward because for the preparation of the tetrapyrranc a bipyrrole can also be used as a central unit to which a benzyl 5-(acetoxymethyl)pyrrole-2-carboxylate can be attached as the terminal pyrrole rings. Debenzylation by catalytic hydrogenation then gives the desired tetrapyrrane building block 68. 

Scheme 6 Synthesis of peptidomimetics containing the pyrrole ring...

Pyrrole Ring Functionalization Gaunt Synthesis of Rhazinicine... 

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