2011
DOI: 10.1021/ol200563j
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Selective and Multiple Functionalization of Pyridines and Alkaloids via Mg- and Zn-Organometallic Intermediates

Abstract: Quinine, nicotine, and related electron-rich amino-substituted pyridines were readily metalated using LiCl-solubilized TMP (2,2,6,6-tetramethylpiperidyl) bases in the presence of BF(3)·OEt(2). A full pyridine functionalization of all five positions of the pyridine ring can be realized by using an appropriate combination of TMP bases in the presence or absence of BF(3)·OEt(2).

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Cited by 57 publications
(57 citation statements)
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“…Nitrogen substituents are also well tolerated in such metalation reactions. Thus, 4-dimethylaminopyridine (DMAP, 45) is conveniently metalated with the system BF 3 ·OEt 2 -TMPMgCl·LiCl (28) leading to the 2-arylated pyridine 46 in 81 % yield after Pd-catalyzed cross-coupling [43]. Similarly, the metalation of (S)-nicotine (47) proceeds selectively in position 6 providing the 3,6-disubstituted pyridine 48 in 92 % yield after a copper-catalyzed allylation (Scheme 11).…”
Section: The Directed Metalation Of Substituted Pyridinesmentioning
confidence: 99%
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“…Nitrogen substituents are also well tolerated in such metalation reactions. Thus, 4-dimethylaminopyridine (DMAP, 45) is conveniently metalated with the system BF 3 ·OEt 2 -TMPMgCl·LiCl (28) leading to the 2-arylated pyridine 46 in 81 % yield after Pd-catalyzed cross-coupling [43]. Similarly, the metalation of (S)-nicotine (47) proceeds selectively in position 6 providing the 3,6-disubstituted pyridine 48 in 92 % yield after a copper-catalyzed allylation (Scheme 11).…”
Section: The Directed Metalation Of Substituted Pyridinesmentioning
confidence: 99%
“…The use of BF 3 ·OEt 2 also allows the functionalization of complex pyridines or quinolines such as quinine (55). A regioselective metalation occurs at position 3 furnishing the arylated quinine 56 in 50 % overall yield after a Pd-catalyzed cross-coupling (Scheme 13) [43].…”
Section: The Directed Metalation Of Substituted Pyridinesmentioning
confidence: 99%
“…[236] Nach einem alternativen Verfahren werden die MagnesiumPyridyltrifluoroborate durch die schrittweise Zugabe von [230] Interessanterweise ermçglicht der Einsatz von BF 3 -modifizierten TMP-Basen in einigen Fällen anschließende Additionsreaktionen ohne Rh-Katalysatoren. [237,238] 3,5-Dibrompyridin (388) wird durch TMPMgCl·BF 3 [230] (À40 8C, 15 min) unter Bildung von Organoborat 389 in Position 4 magnesiert. Zugabe von Pivaldehyd ergibt den angestrebten Alkohol 390 in 79 % Ausbeute.…”
Section: Zinkierungen Unter Verwendung Von Tmpzncl·liclunclassified
“…Nach der Zugabe von Thiophen-2-carbaldehyd wird das Lacton 393 in 70 % Ausbeute erhalten (Schema 68). [238] Pyridine mit Stickstoffsubstituenten werden in ähnlicher Weise funktionalisiert. So liefert die Reaktion von (S)-Nicotin (394) mit BF 3 ·OEt 2 , gefolgt von der Zugabe von TMPMgCl·LiCl (2) bei 0 8C nach 19 h selektiv das 6-metallierte Nicotin 395, [239,240] das nach einer Kupfer(I)-katalysierten Allylierung mit 3-Bromcyclohexen das gewünschte Substitutionsprodukt 396 in 92 % Ausbeute ergibt (Schema 68).…”
Section: Zinkierungen Unter Verwendung Von Tmpzncl·liclunclassified
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