1974
DOI: 10.1002/ange.19740860503
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Phasentransfer‐katalysierte Zweiphasenreaktionen in der präparativen organischen Chemie

Abstract: Quartare Ammonium-und Phosphoniumsalze katalysieren Reaktionen zwischen Substanzen, die sich teilweise in waljriger, teilweise in organischer Phase befinden. Mit solchen Phasentransfer-Katalysatoren kann man viele Umsetzungen, die traditionell in wasserfreiem Medium durchgefiihrt werden, einfacher und schneller gestalten. Dazu gehoren Carbenreaktionen, nucleophile Substitutionen, Alkylierungen von Ketonen und Nitrilen, Wittig-und Darzens-Reaktionen, Ather-Darstellung und Veresterung. Andere Reaktionen, z. B. H… Show more

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Cited by 148 publications
(4 citation statements)
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“…We subjected a number of cyclopropylalkenes to reaction with dichlorocarbene generated by phase-transfer catalysis [4] and characterized the products. The same olefins were subsequently employed in competition experiments with less than equivalent amounts of dichlorocarbene.…”
Section: General Proceduresmentioning
confidence: 99%
“…We subjected a number of cyclopropylalkenes to reaction with dichlorocarbene generated by phase-transfer catalysis [4] and characterized the products. The same olefins were subsequently employed in competition experiments with less than equivalent amounts of dichlorocarbene.…”
Section: General Proceduresmentioning
confidence: 99%
“…The starting materials rac ‐ 8 and rac ‐ 9 were synthesized by dihalocarbene addition onto THP‐protected bicyclopropylidenemethanol 5 ,4a followed by deprotection under acidic conditions (Scheme ). CHCl 3 and NaOH6 were used for rac ‐ 8 , and CF 2 Br 2 , PPh 3 , KF, and 18‐crown‐67 for rac ‐ 9 . It should be noted that the dihalocarbene additions occurred only from the side opposite to the tetrahydropyranyloxymethyl moiety, yielding the endo adducts as single diastereomers.…”
Section: Resultsmentioning
confidence: 99%
“…Though a phase transfer [7,8] was observed with sodium salts or potassium permanganate, preparation [9] of crystalline complexes could (until now) only be accomplished with the former. Na+ (r = 97 pm [10]) fits approximately the [15]crown-5 system (dinner = 170-220 pm [11]); hence, with oligoethers consisting of -CH2-CH2-0 units, it prefers five-fold equatorial coordination (e.g.…”
mentioning
confidence: 96%