Trans‐selektive Olefinsynthesen

Schlosser, Manfred; Christmann, K. F.

doi:10.1002/ange.19660780118

Cited by 45 publications

(13 citation statements)

References 6 publications

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“…The preferential formation of trans olefins in protic solvents was reported for the first time by Schlosser and Christmann in 1967. They explained the phenomenon in terms of the influence of solvent on the solvation of the betaine and an increase in the reversibility of the first step of the Wittig reaction647.…”

Section: The Wittig Reaction In Protic Mediamentioning

confidence: 93%

The Wittig Reaction

Kolodiazhnyi

1999

Phosphorus Ylides

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Section: The Wittig Reaction In Protic Mediamentioning

confidence: 93%

The Wittig Reaction

Kolodiazhnyi

1999

Phosphorus Ylides

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“…In an attempt to optimize the E-isomer ratio of 7c, reaction conditions described by Schlosser et al 18,20 and Schlosser and Christmann 19 have been followed. Thus, 2-trimethylsilylethyl-triphenylphosphonium iodide (4) was first prepared and isolated as described by Seyferth et al 4 The treatment of a suspension of 4 in a 5:3 (v/v) solvent mixture of THF/Et 2 O with phenyllithium/Et 2 O 20 affords ylide 5, which reacts in situ with 6c (Scheme 5).…”

Section: Scheme 4 Schemementioning

confidence: 99%

The Stereoselective Synthesis of Conjugated Allylsilanes

Mahran

Yosef

Effenberger

2006

Phosphorus, Sulfur, and Silicon and the Related Elements

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2-trimethylsilylethylidenetriphenylphosphorane (5) (Seyferth-Wittig reagent) reacts stereoselectively with the carbonyl compounds 6a-f to give the conjugated allylsilanes 7a-f, each as a mixture of E-and Z-isomers. The stereoselectivity of reactions of E-cinnamaldehyde (6c) with 5 has been investigated at different temperatures. A successful E-stereoselective synthesis of 7c was achieved by reacting 5 with E-cinnamaldehyde (6c) under the conditions of a Wittig-Schlosser modification reaction.Structures of the allylsilanes 7a-f were deduced by compatible analytical and spectroscopic (IR, 1 H NMR, 13 C NMR, and GC/MS) measurements. An assignment of the E:Z ratios of 7a-f is based on their 1 H NMR spectral data.

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“…Die Lindlur-Hydrierung des 2,4-Decadiin-1-01s lieferte den Alkohol 5 leider nur als Gemisch der Isomeren (2 Z , 4 Z ) , (2 E , 4 Z), (2 Z,4 E) und (2 E , 4 E ) im Verhaltnis 75 : 8 : 16 : 1. Dagegen liess sich das (E)-4-Decen-2-in-1-01, durch trans-selektive Wittig-Reaktion [22] [23] aufgebaut, recht stereoselektiv zu (2 Z, 4 E)und (2 E, 4 E)-5 hydrieren: nach Lindlar im Verhaltnis 94 : 6, rnit Lithiumaluminiumhydrid im Verhaltnis 2 : 98.…”

Section: )unclassified

Die Strukturdynamik von Pentadienylmetall‐Verbindungen mit endständiger Alkyl‐Gruppe: zugleich «stereoselektive» und «stereodefensive» Synthese eines natürlichen Riechstoffes

Bosshardt

Schlosser

1980

Helvetica Chimica Acta

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The (2 Z, 4 E)-, (2 E , 4 Z)-and (2 E, 4 E)-isomers of 2,4-decadien-1-01 (5) have been obtained with high and predictable stereochemical homogeneity starting from both (2)-and (E)-1,4-decadiene. These hydrocarbons were hydroxylated in a reaction sequence consisting of metallation (by means of s-butyllithium or butyl-1ithiunVpotassium-t-butoxide, giving rise to organometallic intermediates of specific conformation), dimethoxyborylation and oxidation. The different decadienols as well as (2 E , 4 2)-2,4-undecadien-l-01 were converted into the isovalerates, the ester derived from (2 E , 4 Z)-2,4-decadien-l-ol being a natural flavor component.Allylmetall-Verbindungen treten in zwei bevorrech teten Konformationen auf, der ccendo,) -und der ttexo))-Form 1, die beide dank Koplanaritat grosstmoglichen Mesomenegewinn erzielen. Wahrend lithium-und magnesiumorganische Verbindungen vom Allyl-Typ in Sekundenschnelle das Torsionsgleichgewicht zwischen den ctendow-und ccexo>>-Formen einstellen, sind die entsprechenden Natrium-, Kalium-und Casium-Derivate bemerkenswert konformationsstabil. Ausgehend von (Z)-bzw. (E)-2-Alkenen lassen sie sich gezielt erzeugen. Wird die organometallische Zwischenstufe durch Einwirkung eines Elektrophils (El) hinreichend rasch in das Endprodukt 2 umgewandelt, so findet man die gleiche raumliche Anordnung der Substituenten an der Doppelbindung wieder, wie sie in der Alken-Vorstufe vorgegeben war. Wir sprechen dann von einer ccstereodefensivenw Reaktionsfolge.

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Trans‐selektive Olefinsynthesen

Cited by 45 publications

References 6 publications

The Wittig Reaction

The Wittig Reaction

The Stereoselective Synthesis of Conjugated Allylsilanes

Die Strukturdynamik von Pentadienylmetall‐Verbindungen mit endständiger Alkyl‐Gruppe: zugleich «stereoselektive» und «stereodefensive» Synthese eines natürlichen Riechstoffes

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