On the Diastereoselectivity of the Aqueous-Acid-Catalyzed Intramolecular Aldol Condensation of 3-Oxocyclohexaneacetaldehydes

Santis, Barbara De; Iamiceli, Anna Laura; Bettolo, Rinaldo Marini; Migneco, Luisa Maria; Cerichelli, Giorgio; Fabrizi, Giancarlo; Lamba, Doriano

doi:10.1002/(sici)1522-2675(19981216)81:12<2375::aid-hlca2375>3.0.co;2-0

Cited by 28 publications

(38 citation statements)

References 5 publications

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“…1 H NMR and 13 C NMR spectral data were in full agreement with those reported. [32] (AE)-o-Anisyl-2,6-BODOL: The same procedure was used as for the synthesis of (1R,2R,4S,6S)-2-(2-anisyl)-bicyclo[2.2.2]octane-2,6-diol, except that racemic endo-6-hydroxy-bicyclo[2.2.2]octan-2-one was employed instead of the optically active material. The product was obtained as white crystals, m.p.…”

Section: Methodsmentioning

confidence: 97%

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Asymmetric Reduction of Ketones with Catecholborane Using 2,6-BODOL Complexes of Titanium(IV) as Catalysts

Sarvary¹,

Almqvist²,

Frejd³

2001

Chem. Eur. J.

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Reductions performed with Ti(IV) complexes of ligands based on bicyclo[2.2.2]octane diols 5 and 6 are effective catalysts in the reduction of prochiral ketones to optically active alcohols, with catecholborane as the reducing agent. Methyl ketones are favored and enantiomeric excesses (ee) of < or =98% have been achieved with acetophenone as the substrate. Several other substrates were tested, among them 2-octanone, which gave 2-octanol in 87% ee. Further details of the method were examined, for example, temperature, solvent composition, amount of molecular sieves (4 A), and catecholborane quality, as well as the sensitivity of the ligands towards acids. NMR spectroscopic methods were used to gain some insight into the complexes formed between the ligands and [Ti(OiPr)4]. A dimeric structure is proposed for the pre-catalyst.

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Section: Methodsmentioning

confidence: 97%

“…: m.p. 201 [31] and 165.3 ± 167.2 [32] ). 1 H NMR and 13 C NMR spectral data were in full agreement with those reported.…”

Section: Methodsmentioning

confidence: 99%

Asymmetric Reduction of Ketones with Catecholborane Using 2,6-BODOL Complexes of Titanium(IV) as Catalysts

Sarvary¹,

Almqvist²,

Frejd³

2001

Chem. Eur. J.

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“…Die Synthese begann mit der Eintopf‐Michael‐Addition/Aldol‐Kondensation des Ketoesters 6 6 und Enal 7 ,7 gefolgt von einer Krapcho‐Decarboxylierung, was zur Isolation von Cyclohexenon 8 in 60 % Ausbeute über zwei Schritte führte (Schema ). Die gleichzeitige Debenzylierung und konjugierte Reduktion unter Birch‐Bedingungen8 mit anschließender Swern‐Oxidation ergab Ketoaldehyd 9 , der durch säurekatalysierte intramolekulare Aldol‐Reaktion cyclisiert wurde 9. Das so erhaltene racemische Hydroxyketon (±)‐ 5 lag als unbedeutendes Diastereomerengemisch vor und wurde mit Dess‐Martin‐Periodinan10 direkt zum meso‐ Diketon 10 oxidiert.…”

Section: Methodsunclassified

Totalsynthese von (+)‐Crotogoudin

Breitler

Carreira

2013

Angewandte Chemie

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Ein Ring für einen Ring: Die erste Totalsynthese von Crotogoudin, einem 3,4‐seco‐Atisan‐Diterpen, wird beschrieben. Der asymmetrische Zugang zum Bicyclo[2.2.2]octan‐Kern gelang durch Desymmetrisierung eines meso‐Diketons mit Backhefe (LG=Abgangsgruppe, EWG=elektronenziehende Gruppe), und eine SmI2‐induzierte radikalische Cyclopropanöffnung/Ringschluss/Eliminierungs‐Kaskade baute das tetracyclische Grundgerüst von (+)‐Crotogoudin auf. Die Synthese führte zur Revision der publizierten optischen Drehwerte des Naturstoffs und zur Bestimmung seiner absoluten Konfiguration als ent‐Atisan (5R,10R).

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“…13 If the endo product could on these grounds reasonably be considered the thermodynamic product, it was not known which epimer was the kinetic product. Carrying out the reaction at various times, it was shown later that the endo epimer is both the kinetic and thermodynamic product.…”

Section: Endo/exo Products Distribution Under Kinetic and Thermodynammentioning

confidence: 99%

The intramolecular aldol condensation of 3-oxocyclohexaneacetaldehydes: a useful tool in the synthesis of natural products

Migneco¹,

Leonelli²,

Bettolo³

2004

Arkivoc

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On the Diastereoselectivity of the Aqueous-Acid-Catalyzed Intramolecular Aldol Condensation of 3-Oxocyclohexaneacetaldehydes

Cited by 28 publications

References 5 publications

Asymmetric Reduction of Ketones with Catecholborane Using 2,6-BODOL Complexes of Titanium(IV) as Catalysts

Asymmetric Reduction of Ketones with Catecholborane Using 2,6-BODOL Complexes of Titanium(IV) as Catalysts

Totalsynthese von (+)‐Crotogoudin

The intramolecular aldol condensation of 3-oxocyclohexaneacetaldehydes: a useful tool in the synthesis of natural products

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