Nukleophile Alkylierung aromatischer Nitroverbindungen

Kienzle, Frank

doi:10.1002/hlca.19780610140

Cited by 48 publications

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“…Preparation of diacetates. The method described by Kienzle et al [9] used for the acetylation of crystalline astaxanthin, has been modified for biological samples. Purified concentrates, containing 0.5-1.5 mg astaxanthid20 mg lipids, dissolved in 0.2 ml dry pyridine were allowed to react under N2 with 0.2 ml acetic anhydride at RT., overnight.…”

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confidence: 97%

ChemInform Abstract: NATURAL OCCURRENCE OF ENANTIOMERIC AND MESO‐ASTAXANTHIN. 5. EX WILD SALMON (SALMO SALAR AND ONCORHYNCHUS)

Schiedt

Leuenberger

Vecchi

1981

Chemischer Informationsdienst

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confidence: 97%

ChemInform Abstract: NATURAL OCCURRENCE OF ENANTIOMERIC AND MESO‐ASTAXANTHIN. 5. EX WILD SALMON (SALMO SALAR AND ONCORHYNCHUS)

Schiedt

Leuenberger

Vecchi

1981

Chemischer Informationsdienst

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“…However, the reaction is restricted to mono nitrated aromatic compounds and alkyl Grignard reagents. Alkyl lithium compounds react analogously 28. In 1963, Severin and Schmitz performed a reaction between 2,4,6‐trinitrobenzene and alkyl Grignard reagents that leads to a trinitro trialkylcyclohexane 29.…”

Section: Resultsmentioning

confidence: 99%

Synthesis and properties of di‐ and trinitrobenzyl substituted pyridine derivates

Frej¹,

Goeschen²,

Näther³

et al. 2010

J of Physical Organic Chem

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A new method to obtain di‐ and trinitrobenzyl substituted pyridines is presented in this paper. By systematic variation of reaction parameters, the reaction conditions were optimized. The novel synthesis circumvents the commonly used nitration of benzyl pyridines, and thus avoids the nitration of the heterocycle which is a common side reaction. Furthermore, the starting materials for the synthesis of a variety of photochromic nitrobenzyl pyridines are easily accessible. The half‐lives of the phototautomers of several new di‐ and trinitrobenzyl‐substituted pyridines were determined. Copyright © 2010 John Wiley & Sons, Ltd.

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“…Einleitung. -Uber Totalsynthesen der konfigurationsisomeren Astaxanthine la-c (Schema I) ist in der Literatur schon mehrfach berichtet worden [2] [3]; ein weiteres, neues Verfahren geht vom p-Jonongeriist aus [4]. Auch eine Racematspaltung auf der C,,-Stufe ist schon erfolgreich durchgefuhrt worden [ 5 ] .…”

Section: Discussionunclassified

Technische Verfahren zur Synthese von Carotinoiden und verwandten Verbindungen aus 6‐Oxo‐isophoron. III. Ein neues Konzept für die Synthese der enantiomeren Astaxanthine

Zell

Widmer

Lukac

et al. 1981

Helvetica Chimica Acta

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A new and efficient concept for the total synthesis of (3S,3'S)-and (3R,3'R)astaxanthin (la and lc, resp.) in high overall yield and up to 99,2% enantiomeric purity is described. Key intermediates are the (S)-and (R)-acetals 10 and 17, respectively (Scheme 2). These chiral building blocks were synthesized via three different routes: a) functionalization of the enantiomeric 3-hydroxy-6-0x0-isophorons4) 2 and 11, respectively (Scheme 2 ) ; b) optical resolution of 3, 4-dihydroxy-compound4) 19 (Scheme 3), and c) fermentative reductions of 6-0x0-isophorone derivatives (Schemes 4 and 5). -The absolute configurations of the two intermediates 12 and 13 (Scheme 2) have been confirmed by X-ray analysis. -The final steps leading to the enantiomeric astaxanthins are identical with those described for optically inactive astaxanthin [ 11. 1. Einleitung. -Uber Totalsynthesen der konfigurationsisomeren Astaxanthine la-c (Schema I) ist in der Literatur schon mehrfach berichtet worden [2] [3]; ein weiteres, neues Verfahren geht vom p-Jonongeriist aus [4]. Auch eine Racematspaltung auf der C,,-Stufe ist schon erfolgreich durchgefuhrt worden [ 5 ] .In einer vorangegangenen Mitteilung [l] haben wir ein neues Konzept fur die Synthese von (3RS, 3'RS)-Astaxanthin aus 6-0x0-isophoron4) vorgestellt. Schlusselbaustein jener Synthese ist ein racemisches C9-Acetal, welches die Sauerstoff-Funktionen des Astaxanthins in maskierter bzw. geschiitzter Form bereits enthalt. Bei Verwendung der reinen optischen Antipoden 10 und 17 dieses Acetals (s. Schema 2) wiirde dieser Syntheseweg zu den entsprechenden enantiomeren Astaxanthinen la bzw. lc fiihren. Unsere Anstrengungen konzentrierten sich daher auf die Suche und Entwicklung technisch realisierbarer Zugange zu diesen chiralen Bausteinen.

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Nukleophile Alkylierung aromatischer Nitroverbindungen

Abstract: Nucleophilic alkylation of aromatic nitro compounds SummaryAromatic nitro compounds may be alkylated in o-or p-position by treatment with alkyl lithium or alkyl Grignard reagents.

Cited by 48 publications

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ChemInform Abstract: NATURAL OCCURRENCE OF ENANTIOMERIC AND MESO‐ASTAXANTHIN. 5. EX WILD SALMON (SALMO SALAR AND ONCORHYNCHUS)

ChemInform Abstract: NATURAL OCCURRENCE OF ENANTIOMERIC AND MESO‐ASTAXANTHIN. 5. EX WILD SALMON (SALMO SALAR AND ONCORHYNCHUS)

Synthesis and properties of di‐ and trinitrobenzyl substituted pyridine derivates

Technische Verfahren zur Synthese von Carotinoiden und verwandten Verbindungen aus 6‐Oxo‐isophoron. III. Ein neues Konzept für die Synthese der enantiomeren Astaxanthine

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