A copper-catalyzed domino radical cyclization route to benzospiro-indolizidinepyrrolidinones

Stevens, Christian V.; Meenen, Ellen Van; Masschelein, Kurt G. R.; Eeckhout, Yves; Hooghe, Wim; D’hondt, Bart; Nemykin, Victor N.; Zhdankin, Viktor V.

doi:10.1016/j.tetlet.2007.07.211

Cited by 21 publications

(6 citation statements)

References 15 publications

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“…The sequencing of a 5‐ exo‐trig cyclization with a 6‐ endo‐trig reaction ( 118 → 119 ) has been used as an approach to the strychnine alkaloids and the melatonin antagonist tetrahydro‐pyrido[1,2‐ a ]indole core 58. The reverse strategy (a 6‐ endo‐trig followed by 5‐ exo‐trig cyclization) was used in the construction of the carbocycle 121 .…”

Section: Copper Catalyzed Atrcmentioning

confidence: 99%

Copper Catalyzed Atom Transfer Radical Cyclization Reactions

Clark

2016

Eur J Org Chem

131

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Atom transfer radical cyclization (ATRC) is a powerful technique to prepare functionalized 4–10 membered ring systems using transition metal catalysts. In this review recent advances in the use of copper complexes are described. In particular the effect of different ligands on reactivity, selectivity and product outcome are illustrated with application to heterocycle and natural product synthesis. New approaches that increase catalyst efficiency with supplemental reducing agents are reviewed and examples using green solvents, benign reducing agents (e.g. ascorbic acid) and with catalyst loadings as low as 0.05 mol‐% are highlighted. Radical addition to aromatic rings and rearrangement reactions under ATRC conditions as well as application to radical‐polar crossover reactions are also described.

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Section: Copper Catalyzed Atrcmentioning

confidence: 99%

Copper Catalyzed Atom Transfer Radical Cyclization Reactions

Clark

2016

Eur J Org Chem

131

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“…[51] Multi-cyclic systems with high complexity can be afforded by combining two or more ATRC steps in a domino process. Thus, Stevens and co-workers have described the copper-catalyzed synthesis of benzospiro-indolizidinepyrrolidinones by domino ATRC reactions, [52] using CuCl/TMEDA as the catalyst. As shown in Scheme 14 a, the process involves a 5-exo-trig followed by a 6-endo-trig cyclization.…”

Section: Domino Atom Transfer Radical Reactionsmentioning

confidence: 99%

Atom Transfer Radical Reactions as a Tool for Olefin Functionalization – On the Way to Practical Applications

2011

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Transition‐metal‐catalyzed atom transfer radical reactions of halogenated compounds with olefins constitute a versatile tool in organic synthesis within the area of C–C bond forming transformations. The inter‐ or intramolecular versions, atom transfer radical addition (ATRA) or cyclization (ATRC), respectively, lead to the atom‐economic, useful synthesis of compounds that can be further functionalized. This contribution summarizes the recent developments in this area in terms of catalyst design as well as the applicability of this methodology in sequential, domino, or tandem reactions.

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“…In 1998 Ottoni et al, [35] have reported new weaker bases than the traditional NaH, such as NaOH, KOH and NE t3 in ethanol to form N-substituted indole-3carboxaldehyds derivatives 15a-u with 80-100% yields (Scheme 11, Table 1). Some N-alkylation reactions of aldehyde 1 have not been completed under the above mentioned conditions, so the researchers revealed promising alternative bases and conditions [50,51]. For an example, N-alkylation of 1 by benzyl-4-(2iodoethyl)-1-piperidine carboxylate, benzyl-4-(2iodopropyl)-1-piperidine carboxylate, 4-bromobut-1-ene or 5-bromo-2-methyl-pent-2-ene have been first attempted using sodium hydride in THF, but the reaction wasn't completed [50,51].…”

Section: N-alkylation N-acylation and N-sulfonationmentioning

confidence: 99%

“…Some N-alkylation reactions of aldehyde 1 have not been completed under the above mentioned conditions, so the researchers revealed promising alternative bases and conditions [50,51]. For an example, N-alkylation of 1 by benzyl-4-(2iodoethyl)-1-piperidine carboxylate, benzyl-4-(2iodopropyl)-1-piperidine carboxylate, 4-bromobut-1-ene or 5-bromo-2-methyl-pent-2-ene have been first attempted using sodium hydride in THF, but the reaction wasn't completed [50,51]. Grumel et al, [50] and Stevens et al, [51] discovered a promising alternative method by the use of a 3-5M excess of potassium carbonate in acetonitrile and a similar excess of alkenyl bromide under reflux for 24-29hr, to give 16a,b and 17a,b, respectively (Scheme 12).…”

Section: N-alkylation N-acylation and N-sulfonationmentioning

confidence: 99%

“…For an example, N-alkylation of 1 by benzyl-4-(2iodoethyl)-1-piperidine carboxylate, benzyl-4-(2iodopropyl)-1-piperidine carboxylate, 4-bromobut-1-ene or 5-bromo-2-methyl-pent-2-ene have been first attempted using sodium hydride in THF, but the reaction wasn't completed [50,51]. Grumel et al, [50] and Stevens et al, [51] discovered a promising alternative method by the use of a 3-5M excess of potassium carbonate in acetonitrile and a similar excess of alkenyl bromide under reflux for 24-29hr, to give 16a,b and 17a,b, respectively (Scheme 12). On the other hand, the desired N-(substituted) benzylindole-3-carboxaldehydes 18a-e have been prepared in 85-90% yield via the reaction of 1 with different substituted benzyl halides under phase-transfer catalytic (PTC) conditions utilizing triethylbenzyl-ammonium chloride and 50% w/v aqueous NaOH solution in dichloromethane [52] (Scheme 13).…”

Section: N-alkylation N-acylation and N-sulfonationmentioning

confidence: 99%

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