Synthesis of Annelated Substituted Bipyridines and Terpyridines by Cobalt(I)-Catalyzed [2 + 2 + 2] Cycloaddition

Varela, Jesús A.; Castedo, Luís; Saá, Carlos

doi:10.1021/jo9618886

Cited by 61 publications

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References 33 publications

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“…When 25 mol % of 2 was used, only 17% conversion was observed. Due to the hindered nature of these substrates,( 12 ) we postulated that catalyst decomposition may be competitive. Accordingly, we attempted to stabilize CpCo(I).…”

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Diversity Synthesis of Complex Pyridines Yields a Probe of a Neurotrophic Signaling Pathway

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Recognizing the value of including complex pyridines in small-molecule screening collections, we developed a previously unexplored [2 + 2 + 2]-cycloaddition of silyl-tethered diynes with nitriles. The tether provides high regioselectivity, while the solvent THF allows catalytic CpCo(CO)2 to be used without exogenous irradiation. One of the resulting bicyclic and monocyclic (desilylated) pyridines was identified as an inhibitor of neuregulin-induced neurite outgrowth (EC50 = 0.30 µM) in a screen that probes a pathway likely to be involved in breast cancers and schizophrenia.

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Diversity Synthesis of Complex Pyridines Yields a Probe of a Neurotrophic Signaling Pathway

et al. 2008

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“…62 Saa's group developed a short alternative for the synthesis of annelated 3-substituted bipyridines and symmetric 3,3 00 -substituted terpyridines in 1997 (Scheme 5.26a). 64 These compounds are interesting building blocks for the assembly of supramolecular coordination compounds. Later, they described a new, one-step method for synthesizing annelated symmetric 3,3 0 -substituted 2,2 0 -bipyridines from acyclic precursors (Scheme 5.26b).…”

Section: Six-membered and Other Heterocyclesmentioning

confidence: 99%

CHAPTER 5. Cobalt-Catalyzed Heterocycle Synthesis

2014

Catalysis Series

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Cobalt has the chemical configuration [Ar]4s 2 3d 7 and has oxidation states Co(II) and Co(III). Cobalt has many applications in a wide range of areas. In materials, cobalt is primarily used as the metal, for example, in the preparation of magnetic, wear-resistant and high-strength alloys. In biology, cobalt is the active center of coenzymes called cobalamins, the most common example of which is vitamin B 12 . As such, it is an essential trace dietary mineral for all animals. Cobalt in inorganic form is also an active nutrient for bacteria, algae and fungi. In chemistry, various cobalt compounds are used as oxidation catalysts in chemical reactions. Cobalt acetate is used for the conversion of xylene to terephthalic acid, the precursor to the bulk polymer poly(ethylene terephthalate). Typical catalysts are the cobalt carboxylates (known as cobalt soaps). They are also used in paints, varnishes and inks as 'drying agents' through the oxidation of drying oils. The same carboxylates are also used to improve the adhesion of steel to rubber in steel-belted radial tires. Cobalt-based catalysts are also important in reactions involving carbon monoxide. In this chapter, the applications of cobalt catalysts in the synthesis of heterocycles is discussed. Five-Membered HeterocyclesIn 1986, Pattenden and co-workers reported a cobalt-promoted oxidative freeradical cyclization of alkyl bromides, 1 by which functionalized butyrolactones were selectively formed in good yields. In 1990, a convenient method for the stereoselective preparation of trans-2-hydroxymethyltetrahydrofurans by the oxidative cyclization of 5-hydroxy-1-alkenes was developed by Inoki and Mukaiyama. 2 They used bis(1-morpholinocarbamoyl-4,4-dimethyl-1,3-pentanedionato)cobalt(II) [Co(modp) 2 ] as the catalyst with molecular oxygen as the RSC Catalysis Series No.

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“…13 A similar trend was observed when the double cobalt-catalyzed [2+2+2] cycloaddition of 2,6-bis[2-(trimethylsilyl)ethynyl]pyridine and two equivalents of w-alkynyl-a-nitriles gave rise to terpyridines. 11,14 Further interesting bipyridine ligands are the symmetrically 3,3¢-disubstituted 2,2¢-bipyridines, which can be assembled by the double cobalt-catalyzed [2+2+2] cycloaddition of w-alkynyl-a-nitriles and symmetrical 1,3-diynes (Scheme 3). 15 Scheme 3 Synthesis of 3,3¢-disubstituted 2,2¢-bipyridines via the double cobalt-catalyzed [2+2+2] cycloadditions of w-alkynyl-a-nitriles and 1,3-diynes Good control of the regioselectivity was found when using heterosubstituted 1,3-diynes 5.…”

Section: Cobalt-catalyzed [2+2+2] Cycloadditionsmentioning

confidence: 99%

“…+ ticals, can also be assembled by cobalt-catalyzed [2+2+2] cycloadditions (Scheme 6) 17. Dihydrothienopyridine 12 was prepared by the cobalt-catalyzed [2+2+2] cycloaddition of but-3-ynyl thiocyanate(11) with dimethyl acetylenedicarboxylate. Furo-and pyranopyridines 14 (n = 1 and 2, respectively) were constructed using w-alkynyl-anitrile 13 containing an oxygen tether.…”

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Recent Advances in the Synthesis of Pyridines by Transition-Metal-Catalyzed [2+2+2] Cycloaddition

Varela¹,

Saá²

2008

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Synthesis of Annelated Substituted Bipyridines and Terpyridines by Cobalt(I)-Catalyzed [2 + 2 + 2] Cycloaddition

Cited by 61 publications

References 33 publications

Diversity Synthesis of Complex Pyridines Yields a Probe of a Neurotrophic Signaling Pathway

Diversity Synthesis of Complex Pyridines Yields a Probe of a Neurotrophic Signaling Pathway

CHAPTER 5. Cobalt-Catalyzed Heterocycle Synthesis

Recent Advances in the Synthesis of Pyridines by Transition-Metal-Catalyzed [2+2+2] Cycloaddition

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