Chemistry of carbanions. XXII. C- vs. O-acylation of metal enolates

House, Herbert O.; Auerbach, Robert A.; Gall, Martin; Peet, Norton P.

doi:10.1021/jo00943a022

Cited by 152 publications

(48 citation statements)

References 2 publications

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“…This prediction is consistent with the experimental data reported in Ref. [ 3 ] , where an C-acylated product yield < 1 % was observed for this derivative. On the other hand, the methyl and butyl derivatives are predicted to display a very close product yield for alpha-C-acylation which is also consistent with what is experimentally observed in Ref.…”

Section: Frontier Molecular Orbital Analysissupporting

confidence: 93%

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Theoretical study of the C- vs. O-Acylation of metal enolates. Frontier molecular orbital analysis including solvent effects

Saragoni

Contreras

Aizman

1993

Int. J. Quantum Chem.

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An extended version of the Klopman-Salem equation of chemical reactivity, which incorporates the effect of an external electrostatic field in both charge and orbital contributions, has been applied to analyze the reactivity pattern of ambident metal enolates towards acylation reactions in different solvents. The results are consistent with the experimental observation that the proportion of C-acylation product is enhanced for solvents of low polarity where a relevant orbital control contribution is predicted. Comparison between the cisltrans proportion of C-and Qacylation products are also qualitatively accounted for by the FMO analysis. 0

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Section: Frontier Molecular Orbital Analysissupporting

confidence: 93%

“…The existence of these metal enolates as solvent-separated ions is favored by (i) increasing the polarity of the solvent, (ii) the presence of lithium or sodium rather than zinc or magnesium cations, and (iii) by use of the trans rather than the cis stereo-isomer of the enolate [ 3 ] [see Fig. 1 (a)].…”

Section: Introductionmentioning

confidence: 99%

Theoretical study of the C- vs. O-Acylation of metal enolates. Frontier molecular orbital analysis including solvent effects

Saragoni

Contreras

Aizman

1993

Int. J. Quantum Chem.

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“…[22] In addition, although the stereochemistry of the aminoketal C and the face selectivity of the protonation in C were unknown, we think that the intermediate D can have both (R)a nd (S)c onfigurations of the CÀHg bond via E.T he construction of ac arbocycle by Ferrier-type cyclization would result in production of the desired product 29 and regeneration of an Hg(OTf) 2 catalyst. The mechanism and the diastereoselectivity of the reaction that we proposea tp resent are summarized in Scheme 4.…”

Section: Resultsmentioning

confidence: 99%

Total Syntheses of Lepadiformine Marine Alkaloids with Enantiodivergency, Utilizing Hg(OTf)₂‐Catalyzed Cycloisomerization Reaction and their Cytotoxic Activities

Nishikawa

Yamauchi

Kikuchi

et al. 2017

Chemistry A European J

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The enantioselective total syntheses of lepadiformine marine alkaloids, azatricyclic natural products isolated from marine tunicates, were completed. These alkaloids have a unique chemical structure characterized by the trans-1-azadecalin (AB ring system) fused with the spirocyclic ring (AC ring system). Here we found that a cycloisomerization reaction from functionalized linear substrates to a 1-azaspiro[4.5]decane framework corresponding to the AC ring in lepadiformines is promoted by a catalytic amount of mercury(II) triflate (Hg(OTf) ). The total syntheses of (-)-lepadiformines A and B were achieved in 28 % and 21 % overall yields, respectively, through the novel cycloisomerization reaction. The syntheses of (+)- and (-)-lepadiformine C hydrochloride salts also enabled us to determine the absolute configuration of natural lepadiformine C. It has been found that a phenomenon of enantiodivergence occurs in lepadiformine alkaloids from a single species of marine tunicate, Clavelina moluccensis. The cytotoxic activities of synthesized lepadiformine hydrochloride salts and their synthetic intermediates were evaluated.

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“…These spectrum changes implied that the O ‐bound enolate 2‐ O was a kinetically controlled product that gradually tautomerizes to the more stable C ‐bound tautomer 2‐ C in the ketone enolate. The preference of the C ‐bound tautomer of the germyl enolate shares common characteristics with some stannyl enolates derived from ketones and those of the higher elements in Groups 12, 13, and 14, mercury,, thallium and lead . The NMR studies clearly showed the bistability of the O ‐ and C ‐bound germyl enolates.…”

Section: Methodsmentioning

confidence: 58%

First Isolation and Characterization of the Highly Coordinated Group 14 Enolates: Effects of the Coordination Controls on the Geometry and Tautomerization of Germyl Enolates

Konishi

Minami

Hosoi

et al. 2016

Chemistry A European J

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The Group 14 enolates play an important part in many organic reactions. Herein, the reduction of an α-bromo ketone with germanium(II) salts cleanly afforded the corresponding germyl enolate as an isolatable species. This experimental reductive generation of a germyl enolate enabled us to characterize both C- and O-bound tautomers derived from an identical precursor and to unveil the tautomeric mechanisms, including the kinetic parameters and the relative stability of these tautomers, along with confirmation from DFT calculations. Moreover, the highly coordinated germyl enolates were isolated by a stabilization process induced by adding ligands. All products were characterized by NMR spectroscopy and X-ray crystallography.

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Chemistry of carbanions. XXII. C- vs. O-acylation of metal enolates

Cited by 152 publications

References 2 publications

Theoretical study of the C- vs. O-Acylation of metal enolates. Frontier molecular orbital analysis including solvent effects

Theoretical study of the C- vs. O-Acylation of metal enolates. Frontier molecular orbital analysis including solvent effects

Total Syntheses of Lepadiformine Marine Alkaloids with Enantiodivergency, Utilizing Hg(OTf)₂‐Catalyzed Cycloisomerization Reaction and their Cytotoxic Activities

First Isolation and Characterization of the Highly Coordinated Group 14 Enolates: Effects of the Coordination Controls on the Geometry and Tautomerization of Germyl Enolates

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Chemistry of carbanions. XXII. C- vs. O-acylation of metal enolates

Cited by 152 publications

References 2 publications

Theoretical study of the C- vs. O-Acylation of metal enolates. Frontier molecular orbital analysis including solvent effects

Theoretical study of the C- vs. O-Acylation of metal enolates. Frontier molecular orbital analysis including solvent effects

Total Syntheses of Lepadiformine Marine Alkaloids with Enantiodivergency, Utilizing Hg(OTf)2‐Catalyzed Cycloisomerization Reaction and their Cytotoxic Activities

First Isolation and Characterization of the Highly Coordinated Group 14 Enolates: Effects of the Coordination Controls on the Geometry and Tautomerization of Germyl Enolates

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Total Syntheses of Lepadiformine Marine Alkaloids with Enantiodivergency, Utilizing Hg(OTf)₂‐Catalyzed Cycloisomerization Reaction and their Cytotoxic Activities