Selektive katalytische Hydrodefluorierung als Schlüsselschritt zur Synthese bisher unzugänglicher Aminopyridinderivate

Podolan, Gabriel; Lentz, Dieter; Reißig, Hans‐Ulrich

doi:10.1002/ange.201301927

Cited by 15 publications

(2 citation statements)

References 99 publications

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“…We were interested in the synthesis of the new divalent DMAP analogues A (Scheme ) but could not access these new compounds by conventional substitution reactions starting from 4‐halopyridines and trans ‐1,2‐diaminocyclohexane or by other methods 6. However, taking the detour via specifically fluorinated aminopyridine derivatives we could finally prepare these target compounds with reasonable efficacy 7…”

Section: Introductionmentioning

confidence: 99%

Studies on the Synthesis of Specifically Fluorinated 4‐Amino‐ pyridine Derivatives by Regioselective Nucleophilic Aromatic Substitution and Catalytic Hydrodefluorination

et al. 2015

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The reactions of pentafluoropyridine and 2,4,6‐trifluoropyridine with a series of primary and secondary amines were studied. Whereas the nucleophilic aromatic substitution of pentafluoropyridine occurs with high regioselectivity in all cases, providing the expected 4‐aminopyridine derivatives in excellent yields, the regioselectivity of 2,4,6‐trifluoropyridine is dependent on the steric hindrance of the attacking nucleophile. Small nucleophiles such as morpholine attack the 4‐position of the pyridine ring with high preference, but more bulky diamines attack the 2‐ and 4‐positions leading to the formation of three regioisomeric products. (R,R)‐1,2‐Diaminocyclohexane as moderately bulky diamine reacted with 2,4,6‐trifluoropyridine to afford the desired bis(4‐aminopyridinyl)cyclohexane derivative in 30% yield. For hydrodefluorination two methods were examined. A two‐step procedure employing hydrazine and subsequently copper(II) sulfate removed just one fluorine substituent, but is not sufficiently high yielding for the reduction of more complex substrates. With the system titanocene difluoride as pre‐catalyst and diphenylsilane as reducing agent we were able to selectively remove fluorine substituents at positions C‐2 and C‐4 of a variety of 4‐aminopyridine derivatives. This protocol allows the synthesis of compounds such as the divalent chiral 4‐(dimethylamino)pyridine (DMAP) analogue (R,R)‐trans‐N,N′‐dimethyl‐N,N′‐bis(pyridin‐4‐yl)cyclohexane‐1,2‐diamine with fair overall yield.

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Section: Introductionmentioning

confidence: 99%

Studies on the Synthesis of Specifically Fluorinated 4‐Amino‐ pyridine Derivatives by Regioselective Nucleophilic Aromatic Substitution and Catalytic Hydrodefluorination

et al. 2015

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“…Unserem Interesse an Analoga von 4-(Dimethylamino)pyridin (DMAP) [13] folgend wählten wir Dimethylaminosubstituierte Terpyridine als Zielstrukturen. Der elektronenspendende Effekt von Aminogruppen in para-Stellung zum Pyridinstickstoffatom induziert bei Terpyridinen einen starken s-Donorcharakter und vermag photophysikalische [14] sowie andere Eigenschaften [15] von Übergangsmetallkomplexen stark zu beeinflussen.…”

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Extrem starke Lewis‐Basen – Synthese und Methylkationaffinitäten von Dimethylamino‐substituierten Terpyridinen

et al. 2014

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Es wird eine vielseitig einsetzbare Methode zur Herstellung von funktionalisierten 2,2':6',2''-Terpyridinen vorgestellt, bei der die äußeren Pyridinringe über Cyclisierungsreaktionen aufgebaut werden. Die Vorstufen -Bis-b-ketoenamide -werden aus in 4-Position substituierten 2,6-Pyridindicarbonsäuren und Acetylaceton oder dem entsprechenden Enaminoketon hergestellt. Ihre Cyclisierung erfolgt mithilfe von Trifluormethansulfonsäuretrimethylsilylester durch eine zweifache intramolekulare Kondensation.

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Synthesis and Photophysical Properties of Substituted 2,2′:6′,2′′‐Terpyridine Derivatives and Analogous Compounds with a Central Thiophene Ring

Hommes

Reißig

2016

Asian J Org Chem

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New 2,2':6',2''-terpyridine derivatives werep repared by Suzuki-Miyaura coupling of the corresponding 4,4''-bis(nonaflate) with the appropriate boronic acid derivatives. The corresponding 4,4''-diazido terpyridine derivative allowed ac opper(I)-promoted click reactionw ithp henyl acetylene to provide the bis(triazolyl)-substitutedt erpyridine in excellent yield. For comparison, analogs or terpyridines with ac entralt hiophene ring weres ynthesized by applying the well proven cyclocondensation reactiono ft he bis(b-ketoenamide) derived from 2,5-thiophenedicarboxylica cid. The UV/Viss pectra as well as the fluorescences pectra of these new compounds were recorded and compared with related heterocycles.Scheme1.Approachtof unctionalized2,2':6',2''-terpyridine derivatives I with highlighted functional groups (pink balls)from 2,6-pyridinedicarboxylic acid derivatives II and b-ketoenamine III.[a] Dr.P .Hommes,P rof. Dr.H .-U.ReissigScheme5.Synthesis of bis(nonaflate) 16 starting from 2,5-thiophenedicarboxylic acid 13.Scheme6.Suzuki-Miyaurac ouplingsofb is(nonaflate) 16 leadingtos ubstituted compounds 17 and 18.

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Selektive katalytische Hydrodefluorierung als Schlüsselschritt zur Synthese bisher unzugänglicher Aminopyridinderivate

Cited by 15 publications

References 99 publications

Studies on the Synthesis of Specifically Fluorinated 4‐Amino‐ pyridine Derivatives by Regioselective Nucleophilic Aromatic Substitution and Catalytic Hydrodefluorination

Studies on the Synthesis of Specifically Fluorinated 4‐Amino‐ pyridine Derivatives by Regioselective Nucleophilic Aromatic Substitution and Catalytic Hydrodefluorination

Extrem starke Lewis‐Basen – Synthese und Methylkationaffinitäten von Dimethylamino‐substituierten Terpyridinen

Synthesis and Photophysical Properties of Substituted 2,2′:6′,2′′‐Terpyridine Derivatives and Analogous Compounds with a Central Thiophene Ring

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