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2 pages, 126 KiB

Open AccessEditorial

Carbanion Chemistry from Carboxylic Acids: a Special Issue in Honor of Professor Ramón Mestres on his 65th Birthday.

by Margarita Parra and Salvador Gil

Molecules 2004, 9(5), 264-265; https://doi.org/10.3390/90500264 - 30 Apr 2004

Viewed by 6151

Abstract

This special issue of Molecules is to honour the 65^th birthday of Professor Ramón Mestres.[...] Full article

(This article belongs to the Special Issue Carbanion chemistry from Carboxylic acids in honor of Prof. Ramón Mestres on his 65th anniversary)

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10 pages, 198 KiB

Open AccessArticle

A Novel Strategy Towards the Asymmetric Synthesis of Orthogonally Funtionalised 2-N-Benzyl-N-α-methylbenzylamino- 5-carboxymethyl-cyclopentane-1-carboxylic acid.

by Narciso M. Garrido, Mohamed M. El Hammoumi, David Díez, Mercedes García and Julio G. Urones

Molecules 2004, 9(5), 373-382; https://doi.org/10.3390/90500373 - 30 Apr 2004

Cited by 8 | Viewed by 10421

Abstract

The asymmetric synthesis of the orthogonally funtionalised compounds tert-butyl 2-N-benzyl-N-α-methylbenzylamino-5-methoxycarbonylmethylcyclopentane- 1-carboxylate and methyl 2-N-benzyl-N-α-methylbenzylamino-5–carboxymethylcyclo- pentane-1-carboxylate by a domino reaction of tert-butyl methyl (E,E)-octa-2,6- diendioate with lithium N-α-methylbenzyl-N-benzylamide initiated by a Michael addition, subsequent 5-exo-trig intramolecular cyclisation and posterior selective hydrolysis with trifluoroacetic acid [...] Read more.

The asymmetric synthesis of the orthogonally funtionalised compounds tert-butyl 2-N-benzyl-N-α-methylbenzylamino-5-methoxycarbonylmethylcyclopentane- 1-carboxylate and methyl 2-N-benzyl-N-α-methylbenzylamino-5–carboxymethylcyclo- pentane-1-carboxylate by a domino reaction of tert-butyl methyl (E,E)-octa-2,6- diendioate with lithium N-α-methylbenzyl-N-benzylamide initiated by a Michael addition, subsequent 5-exo-trig intramolecular cyclisation and posterior selective hydrolysis with trifluoroacetic acid is reported. Full article

(This article belongs to the Special Issue Carbanion chemistry from Carboxylic acids in honor of Prof. Ramón Mestres on his 65th anniversary)

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8 pages, 179 KiB

Open AccessArticle

Nucleophilic Benzoylation Using a Mandelic Acid Dioxolanone as a Synthetic Equivalent of the Benzoyl Carbanion. Oxidative Decarboxylation of α-Hydroxyacids

by Gonzalo Blay, Isabel Fernández, Belén Monje and José R. Pedro

Molecules 2004, 9(5), 365-372; https://doi.org/10.3390/90500365 - 30 Apr 2004

Cited by 5 | Viewed by 9507

Abstract

The synthesis of alkyl aryl ketones using a mandelic acid dioxolanone as a synthetic equivalent (Umpolung) of the benzoyl carbanion is reported. The methodology involves alkylation of the mandelic acid dioxolanone, hydrolysis of the dioxolanone moiety in the alkylated products and oxidative decarboxylation [...] Read more.

The synthesis of alkyl aryl ketones using a mandelic acid dioxolanone as a synthetic equivalent (Umpolung) of the benzoyl carbanion is reported. The methodology involves alkylation of the mandelic acid dioxolanone, hydrolysis of the dioxolanone moiety in the alkylated products and oxidative decarboxylation of the resulting α-hydroxyacids. The last step is carried out in a catalytic aerobic way using a Co (III) complex in the presence of pivalaldehyde under very mild conditions. Full article

(This article belongs to the Special Issue Carbanion chemistry from Carboxylic acids in honor of Prof. Ramón Mestres on his 65th anniversary)

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16 pages, 219 KiB

Open AccessArticle

Polymer-Supported Cinchona Alkaloid-Derived Ammonium Salts as Recoverable Phase-Transfer Catalysts for the Asymmetric Synthesis of α-Amino Acids

by Rafael Chinchilla, Patricia Mazón and Carmen Nájera

Molecules 2004, 9(5), 349-364; https://doi.org/10.3390/90500349 - 30 Apr 2004

Cited by 31 | Viewed by 11442

Abstract

Alkaloids such as cinchonidine, quinine and N-methylephedrine have been N-alkylated using polymeric benzyl halides or co-polymerized and then N-alkylated, thus affording a series of polymer-supported chiral ammonium salts which have been employed as phase-transfer catalysts in the asymmetric benzylation of an N-(diphenylmethylene)glycine ester. [...] Read more.

Alkaloids such as cinchonidine, quinine and N-methylephedrine have been N-alkylated using polymeric benzyl halides or co-polymerized and then N-alkylated, thus affording a series of polymer-supported chiral ammonium salts which have been employed as phase-transfer catalysts in the asymmetric benzylation of an N-(diphenylmethylene)glycine ester. These new polymeric catalysts can be easily recovered by simple filtration after the reaction and reused. The best ee’s were achieved when Merrifield resin-anchored cinchonidinium ammonium salts were employed. Full article

(This article belongs to the Special Issue Carbanion chemistry from Carboxylic acids in honor of Prof. Ramón Mestres on his 65th anniversary)

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19 pages, 235 KiB

Open AccessArticle

Masked ω-Lithio Ester Enolates: Synthetic Applications

by Miguel Yus, Rosario Torregrosa and Isidro M. Pastor

Molecules 2004, 9(5), 330-348; https://doi.org/10.3390/90500330 - 30 Apr 2004

Cited by 11 | Viewed by 11957

Abstract

The protocol of lithiation by means of lithium and a catalytic (5% molar) amount of DTBB (4,4’-di-tert-butylbiphenyl), applied to ω-chloro ortho ester 6 under Barbier-type conditions gives, after final acid-catalyzed methanolysis, the corresponding functionalized esters 8 or 9 (for chlorotrimethylsilane as electrophile) or, [...] Read more.

The protocol of lithiation by means of lithium and a catalytic (5% molar) amount of DTBB (4,4’-di-tert-butylbiphenyl), applied to ω-chloro ortho ester 6 under Barbier-type conditions gives, after final acid-catalyzed methanolysis, the corresponding functionalized esters 8 or 9 (for chlorotrimethylsilane as electrophile) or, after ortho ester deprotection and acid catalyzed treatment, the δ-lactones 11. The procedure is also practical for bicyclic ortho esters 14: the β-chloro OBO ester derivate generates the γ- lactones 15 and the γ-chloro OBO ester gives corresponding esters 8. Full article

(This article belongs to the Special Issue Carbanion chemistry from Carboxylic acids in honor of Prof. Ramón Mestres on his 65th anniversary)

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7 pages, 166 KiB

Open AccessArticle

1-Hydroxymethyl-4-phenylsulfonybutadiene, a Versatile Building Block for the Synthesis of 2,3,4-Trisusbtituted Tetrahydrothiophenes

by David Díez, M. Templo Benéitez, Isidro S. Marcos, N. M. Garrido, P. Basabe and Julio G. Urones

Molecules 2004, 9(5), 323-329; https://doi.org/10.3390/90500323 - 30 Apr 2004

Cited by 3 | Viewed by 8137

Abstract

A method to synthesize chiral 2,3,4-trisusbtituted tetrahydrothiophenes in both enantiomerically pure forms starting from 1-hydroxymethyl-4-phenylsulfonylbutadiene is described. Full article

(This article belongs to the Special Issue Carbanion chemistry from Carboxylic acids in honor of Prof. Ramón Mestres on his 65th anniversary)

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22 pages, 283 KiB

Open AccessArticle

From Labdanes to Drimanes. Degradation of the Side Chain of Dihydrozamoranic Acid.

by Jesús M.L. Rodilla, D. Díez, J. G. Urones and Pedro M. Rocha

Molecules 2004, 9(5), 300-322; https://doi.org/10.3390/90500300 - 30 Apr 2004

Cited by 3 | Viewed by 9572

Abstract

A new route for the degradation of the saturated side chain of dihydrozamoranic acid has been devised, giving an advanced intermediate, compound 14, useful for the synthesis of insect antifeedants such as warburganal and polygodial. Full article

(This article belongs to the Special Issue Carbanion chemistry from Carboxylic acids in honor of Prof. Ramón Mestres on his 65th anniversary)

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13 pages, 229 KiB

Open AccessArticle

Synthesis of Highly Functionalised Enantiopure Bicyclo[3.2.1]- octane Systems from Carvone

by Antonio Abad, Consuelo Agulló, Ana C. Cuñat, Ignacio De Alfonso, Ismael Navarro and Noelia Vera

Molecules 2004, 9(5), 287-299; https://doi.org/10.3390/90500287 - 30 Apr 2004

Cited by 15 | Viewed by 12852

Abstract

The commercially available monoterpene carvone has been efficiently convertedinto the tricyclo[3.2.1.0^2.7]octane and bicyclo[3.2.1]octane systems characteristic of somebiologically active compounds. The sequence used for this transformation involves as keyfeatures an intramolecular Diels-Alder reaction of a 5-vinyl-1,3-cyclohexadiene and acyclopropane ring opening. Full article

(This article belongs to the Special Issue Carbanion chemistry from Carboxylic acids in honor of Prof. Ramón Mestres on his 65th anniversary)

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9 pages, 268 KiB

Open AccessArticle

Self-assembly of [2]Rotaxane Exploiting Reversible Pt(II)- Pyridine Coordinate Bonds

by Pablo Ballester, Magdalena Capó, Antoni Costa, Pere M. Deyà, Antoni Frontera and Rosa M. Gomila

Molecules 2004, 9(5), 278-286; https://doi.org/10.3390/90500278 - 30 Apr 2004

Cited by 8 | Viewed by 8506

Abstract

A dinuclear self-assembled cationic macrocycle based on Pt(II)-N(pyridine) coordinative bonds and having competitive triflate anions, as metal counterions, is used in the construction of [2]rotaxane and [2]pseudorotaxane architectures assisted by hydrogen bonding. The kinetic lability of the Pt(II)-N(pyridine) coordinative bond controls the dynamics [...] Read more.

A dinuclear self-assembled cationic macrocycle based on Pt(II)-N(pyridine) coordinative bonds and having competitive triflate anions, as metal counterions, is used in the construction of [2]rotaxane and [2]pseudorotaxane architectures assisted by hydrogen bonding. The kinetic lability of the Pt(II)-N(pyridine) coordinative bond controls the dynamics of the [2]rotaxane. Full article

(This article belongs to the Special Issue Carbanion chemistry from Carboxylic acids in honor of Prof. Ramón Mestres on his 65th anniversary)

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12 pages, 205 KiB

Open AccessArticle

Investigations into the Use of a Polyfluorooctanol as an Auxiliary Component for an Aldol Reaction

by Jason Eames and Hasina Khanom

Molecules 2004, 9(5), 266-277; https://doi.org/10.3390/90500266 - 30 Apr 2004

Cited by 4 | Viewed by 8623

Abstract

Results are reported on the efficiency of polyfluorooctanol as a perfluorousauxiliary component in the aldol reaction between the enolate derived frompolyfluorooctyl acetate and 2-fluorobenzaldehyde. Reduction of the correspondingpolyfluoro β-hydroxy ester with Super Hydride^® gave the required 1,3-diol in good yield. Full article

(This article belongs to the Special Issue Carbanion chemistry from Carboxylic acids in honor of Prof. Ramón Mestres on his 65th anniversary)

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