Efficient and versatile single pot approach to dipyrromethanes and bis(heterocyclyl)methanes

Singh, Kamaljit; Behal, Sonia; Hundal, Maninder Singh

doi:10.1016/j.tet.2005.04.029

Cited by 25 publications

(1 citation statement)

References 64 publications

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“…Reformatsky and Mannich reactions with the participation of the C=N bond of the open tautomeric form of chiral, non-racemic oxazolidines provided a stereoselective procedure for the synthesis of -amino esters [3]. Because of their ringchain tautomeric character, oxazolidines and tetrahydro-1,3-oxazines have been applied as aldehyde sources or aldehyde protecting groups in various inter-or intramolecular carbon-transfer reactions [4,5]. The differences in the reactivities of the ring-chain tautomeric forms of 1,3-O,N-heterocycles have been utilized in the diastereoselective transformations of chiral, non-racemic amino alcohols towards bicyclic lactams or 1,2,4-trisubstituted oxazolidines [6,7].…”

Section: Introductionmentioning

confidence: 99%

Substituent effects in the ring‐chain tautomerism of 4‐alkyl‐2‐aryl substituted oxazolidines and tetrahydro‐1,3‐oxazines

Juhász¹,

Lázár²,

Fülöp³

2007

Journal of Heterocyclic Chem

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The condensation products of 2-aminoethanol or 3-aminopropanol (bearing an alkyl substituent on the carbon adjacent to the nitrogen) with substituted benzaldehydes proved to exist in CDCl 3 at 300 K as threecomponent tautomeric mixtures of the diastereomeric five-or six-membered 1,3-O,N-heterocyclic ring forms and the corresponding imines. For each equilibrium, the electronic effects of the 2-aryl substituents were characterized by the Hammett equation. The steric effects of the alkyl groups could be described by Hansch-type equations for the equilibria involving oxazolidine ring forms. While the alkyl substituents did not cause any significant effect on the ring cis-chain and the ring trans-chain equilibria for tetrahydro-1,3-oxazines, increasing bulk of the 4-alkyl group increased the stability of the cyclic tautomers for the analogous oxazolidines.

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Section: Introductionmentioning

confidence: 99%

Substituent effects in the ring‐chain tautomerism of 4‐alkyl‐2‐aryl substituted oxazolidines and tetrahydro‐1,3‐oxazines

Juhász¹,

Lázár²,

Fülöp³

2007

Journal of Heterocyclic Chem

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Synthesis of a Novel Type of 2,3′‐BIMs via Platinum‐Catalysed Reaction of Indolylallenes with Indoles

Cooper

Alonso

Eagling

et al. 2018

Chemistry A European J

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Optimisation, scope and mechanism of the platinum‐catalysed addition of indoles to indolylallenes is reported here to give 2,3′‐BIMs with a novel core structure very relevant for pharmaceutical industry. The reaction is modulated by the electronic properties of the substituents on both indoles, with the 2,3′‐BIMs favoured when electron donating groups are present. Although simple at first, a complex mechanism has been uncovered that explains the different behaviour of these systems with platinum when compared with other metals (e.g. gold). Detailed labelling studies have shown Pt‐catalysed 6‐endo‐trig cyclisation of the indollylallene as the first step of the reaction and the involvement of two cyclic vinyl‐platinum intermediates in equilibrium through a platinum carbene, as the key intermediates of the catalytic cycle towards the second nucleophilic attack and formation of the BIMs.

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