The REACTION OF CERTAIN UNSYMMETRICAL Β-Diketones WITH ETHYLMAGNESIUM BROMIDE

Chaney, Alan; Astle, Melvin J.

doi:10.1021/jo01141a009

Cited by 9 publications

(1 citation statement)

References 2 publications

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“…The b-hydroxyketone 3 with a tertiary hydroxy group was synthesized by a Grignard reaction between methyl magnesium iodide and 3,5-heptanedione. 31 Compound 4 was synthesized by an LDA-mediated aldol reaction between 4heptanone and n-propanal, analogous to 2, yielding a product 71/29 syn/anti. The experiments were carried out according to the general method and the progress of reactions was monitored at 3, 24, 48, 72 and 96 h.…”

Section: Investigation Of Analoguesmentioning

confidence: 99%

Vegetables as biocatalysts in stereoselective hydrolysis of labile organic compounds

Bohman¹,

Cavonius²,

Unelius

2009

Green Chem.

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Hydrolysis of labile esters of b-hydroxyketones has been performed with whole plant tissue from various vegetables. The pheromone 5-hydroxy-4-methyl-3-heptanone (1) was used as the model compound. Hydrolysis of acetates and benzoates of 1 was unsuccessful using normal conditions of ester hydrolysis, both by chemical hydrolysis and by the means of commercial lipases. When, however, whole cells of carrot, celery root, eggplant, parsley root, parsnip and potato were used as reagents, hydrolysis of the acetates was successful. At low conversion the hydrolysis was stereoselective and at total conversion virtually no formation of by-products was observed. The selectivity varied among the eight vegetables that were evaluated. Methods of preparation and substrate-to-plant ratio were examined. Furthermore, acetates and benzoates of three analogous compounds [5-hydroxy-3-heptanone (2), 5-hydroxy-5-methyl-3-heptanone (3) and 5-ethyl-6-hydroxy-4-octanone (4)] were hydrolyzed by potato and sweet potato to various degrees, indicating that the method is general for the mild and stereoselective hydrolysis of secondary b-alkoxy-and b-aryloxyketones.

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Section: Investigation Of Analoguesmentioning

confidence: 99%

Vegetables as biocatalysts in stereoselective hydrolysis of labile organic compounds

Bohman¹,

Cavonius²,

Unelius

2009

Green Chem.

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Präparative Aspekte der aus β‐Dicarbonylverbindungen synthetisierbaren 1,3‐Dithiolane

et al. 1982

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Aus 1,2-Ethandithiol(l) und den PDicarbonylverbindungen 2 werden die 1.3-Dithiolane 3 erhalten, die regioselektiven Reaktionen an der noch freien Carbonylfunktion zuganglich sind. So lassen sich die Derivate der P-Ketocarbonsaureester zu den Carbonsauren 4 hydrolysieren, die bei der Veresterung mit den Alkanolen 5 die estergruppenmodifizierten 1,3-Dithiolane 3 liefern. Einwirkung von Trimethyloxonium-tetrafluoroborat ergibt die Monodithiolaniumsalze 6 , die bei der Hydrolyse rasch in 2 und die Vinylthioether 8 zerfallen. Umsetzung von 3 mit den Grignardreagenzien 10 ergibt die 2-(2-Hydroxyalkyl)-l,3-dithiolane 11. Dethioacetalisierung von 11 mit HgO/BF, fuhrt zu den P-Hydroxyketonen 12. Die Riickspaltung von 3 zu 2 gelingt nur in mBRigen Ausbeuten. -SchlieBlich wird noch die Darstellung des empfindlichen Silylenolethers 13 aus 3 g beschrieben. Preparative Aspects of 1,3-Dithiolanes Synthesizable from p-Dicarbonyl CompoundsThe reaction of 1,2-ethanedithiol (1) with the P-dicarbonyl compounds 2 leads to the 1,3-dithiolanes 3 which are accessible to regioselective reactions at the free carbonyl function. Thus the derivatives of the P-keto acid esters can be hydrolyzed to give the corresponding carboxylic acids 4 which make the ester group modified 1,3-dithiolanes 3 accessible in good yields. Addition of trimethyloxonium tetrafluoroborate produces the monodithiolanium salts 6 which on hydrolysis rapidly decompose into 2 and the vinyl thioethers 8. Reaction of 3 with the Grignard reagents 10 yields the 2-(2-hydroxyalkyl)-l,3-dithiolanes 11. Dethioacetalization of 11 with HgO/BF, leads to the khydroxy ketones 12. The retro reaction of 3 leads to the basic compounds 2 which, however, are obtained only in moderate yields. -Finally the performance of the sensitive silylenol ether 13 starting from 3g is described.Cyclische Thioacetale vom Typ des 1 ,3-Dithians1) und des 1,3-Dithiolan~~.~) sind Schutzgruppen fur Carbonylfunktionen, die infolge ihrer Bestandigkeit im sauren Medium 0-Acetalen bei bestimmten Reaktionen vorzuziehen sind. Zudem sind heute zahlreiche wirkungsvolle Hydrolysemethoden zur Regenerierung der Carbonylgruppe bekannt4). Wir berichteten kurzlich uber 2,2-disubstituierte 1,3-Dithiane, die zum partiellen Schutz der CO-Funktionen von 1,3-Dicarbonylverbindungen eingesetzt werden kdnnen 5-6).Unsere weiteren Untersuchungen ergaben, dal3 auch 1 ,ZEthandithiol ein geeignetes Reagenz zur C = 0-Maskierung bei b-Diketoverbindungen darstellt, wobei im Vergleich zum Sechsring-System neben den ahnlich guten Ausbeuten der 1,3-Dithiolane der Kostenersparnis (ca. 50%) erhebliche Bedeutung zukomrnt. Die 1,3-Dithiolane 3 0 Verlag

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Action des organomagnésiens sur les composés β-dicarbonylés III. Mécanisme de l'addition du bromure de phénylmagnésium et du chlorure de benzylmagnésium sur l'acétylacétate d'éthyle.

Canonne

Castelli

1970

Tetrahedron Letters

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The REACTION OF CERTAIN UNSYMMETRICAL Β-Diketones WITH ETHYLMAGNESIUM BROMIDE

Cited by 9 publications

References 2 publications

Vegetables as biocatalysts in stereoselective hydrolysis of labile organic compounds

Vegetables as biocatalysts in stereoselective hydrolysis of labile organic compounds

Präparative Aspekte der aus β‐Dicarbonylverbindungen synthetisierbaren 1,3‐Dithiolane

Action des organomagnésiens sur les composés β-dicarbonylés III. Mécanisme de l'addition du bromure de phénylmagnésium et du chlorure de benzylmagnésium sur l'acétylacétate d'éthyle.

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