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Juan F Sanz-Cervera

Publications and source records attributed to Juan F Sanz-Cervera.

13 recordsLinked to original sources
PubMed2006

Asymmetric synthesis of fluorinated cyclic beta-amino acid derivatives through cross metathesis.

The asymmetric synthesis of several fluorinated cis-2-aminocycloalkane carboxylic acids (cis-2-ACACs) with a cross metathesis (CM) reaction as the key step has been carried out, constituting the first time a metathesis protocol has been undertaken with fluorinated imidoyl chlorides. Subsequent chemoselective hydrogenation of the olefin moiety, Dieckmann condensation, and stereoselective reduction of the iminic double bond afforded the corresponding beta-amino esters with several ring sizes. The asymmetric version of the process was achieved by using (-)-8-phenylmenthol as a chiral auxiliary.

Amino Acids↗
PubMed2006

Asymmetric synthesis of new beta,beta-difluorinated cyclic quaternary alpha-amino acid derivatives.

The synthesis of new beta,beta-difluorinated cyclic quaternary alpha-amino acid derivatives 1 in which a ring-closing metathesis reaction (RCM) constitutes the key step is described. The approach employs imidoyl chlorides 3 as fluorinated building blocks, and the overall process involves the stereoselective creation of a quaternary stereocenter. Complete selectivity was achieved when (R)-phenylglycinol methyl ether was used as chiral auxiliary, allowing for the preparation of new six-membered cyclic fluorinated alpha-amino acids as single enantiomers.

Amino Acids↗
PubMed2006

Synthesis and biological evaluation of new bicyclic fluorinated uracils through ring-closing metathesis.

Two families of bicyclic fluorinated uracils have been prepared starting from a gem-difluorinated unsaturated nitrile, by means of a ring-closing metathesis reaction to form the new ring, which is fused at the C-5/C-6 or N-1/C-6 positions of the uracil moiety. The selective formation of olefin regioisomers in the metathesis process can be controlled according to the reaction conditions (catalyst, solvent, and temperature). The acaricidal activities of the resulting compounds have also been investigated.

Fluorine↗
PubMed2006

Fluorous (trimethylsilyl)ethanol: a new reagent for carboxylic acid tagging and protection in peptide synthesis.

Starting with a fluorous analogue of 2-(trimethylsilyl)ethanol, we have designed an easy method for preparing a new fluorous tag ((F)TMSE) for the protection of carboxylic acids. Because mild conditions are employed in the tag cleavage (TBAF in the presence of 4 A molecular sieves, which prevent racemization), this tag can be advantageously used in the synthesis of peptides and modified peptides, as we have demonstrated with several examples, including the fluorous synthesis of short alpha- and beta-peptides as well as of modified fluorinated retropeptides.

Carboxylic Acids↗
PubMed2006

Role of the gem-difluoro moiety in the tandem ring-closing metathesis-olefin isomerization: regioselective preparation of unsaturated lactams.

Careful selection of the metathesis catalyst, solvent, and reaction conditions allows for the efficient and regioselective synthesis of isomeric fluorinated and nonfluorinated lactam derivatives II and III from precursor amides I through a ring-closing metathesis (RCM) reaction or a tandem RCM-isomerization protocol, respectively. The presence of the gem-difluoro moiety in the starting materials exerts a pivotal effect by directing the isomerization step, making the overall tandem transformation a regioselective process. The scope, limitations, and synthetic usefulness of this protocol are also discussed.

Journal Article↗
PubMed2005

Highly enantioselective synthesis of fluorinated gamma-amino alcohols through proline-catalyzed cross-Mannich reaction.

A new, simple route for the synthesis of fluorinated beta-alkyl gamma-amino alcohols in optically pure form in only two steps and featuring proline catalysis from inexpensive and readily available starting materials is described. The applied strategy allows for the introduction of diversity into both the beta-fluoroalkyl and alpha-alkyl groups of these compounds. [reaction: see text]

Amino Alcohols↗
PubMed2005

Sesquiterpenes from Centaurea aspera.

The aerial parts of two subspecies of Centaurea aspera L. (Asteraceae) yielded the germacranolides 1a-h, 2, 3, 4 and 5, the elemane derivatives 6d and 6f, the lignan matairesinol, the degraded terpene loliolide, and the onopordopicrin-valine dimeric adduct 7. From these, compounds 1e, 3 and 6d are natural products. The chemical composition of the two subspecies is very similar, a circumstance which does not support a taxonomic subdivision of the species.

Centaurea↗
PubMed2004

A versatile synthesis of fluorinated uracils in solution and on solid-phase.

[reaction: see text] An efficient and convenient two-step synthesis of new fluorinated uracils is described. The first step involves the condensation of an ester enolate with a fluorinated nitrile to furnish fluorinated beta-enamino esters. In turn, these compounds react with organic isocyanates or isothiocyanates to give C-6 fluorinated uracils or thiouracils, respectively, in excellent yields. This synthesis has been successfully adapted to solid-phase conditions with high diversity, thereby facilitating the creation of small (thio)uracil libraries.

Hydrocarbons, Fluorinated↗
PubMed2003

Studies on the biosynthesis of asperparaline A: origin of the spirosuccinimde ring system.

The primary amino acid building blocks that constitute asperparaline A have been determined through feeding and incorporation of 13C-labeled intermediates. The beta-methyl proline residue is constituted from (S)-isoleucine, the novel spiro-succinime moiety is derived from the oxidative degradation of (S)-tryptophan, and (S)-adenosylmethionine contributes the two N-methyl residues. In addition, it was found that the incorporation of 13C-labeled acetate into the single isoprene unit clearly demonstrates that the isoprene moiety is derived from the mevalonate pathway.

Alkaloids↗
PubMed2003

Diastereoselective synthesis of fluorinated, seven-membered beta-amino acid derivatives via ring-closing metathesis.

[reaction: see text] Cis and trans seven-membered gamma,gamma-difluorinated beta-amino acid derivatives (III) have been prepared with a sequence that starts with imidoyl halides (I), which are condensed with suitable ester enolates to give intermediates (II). These, in turn, can be cyclized by means of a ring-closing olefin metathesis reaction and the product stereoselectively reduced to yield compounds (III) in good overall yields.

Amino Acids↗
PubMed2002

A concise, asymmetric synthesis of tetramic acid derivatives.

[reaction: see text] A simple, asymmetric synthesis of tetramic acid derivatives is described in this paper. The key step is a carbonyl transfer from carbonyldiimidazole (CDI) to alpha-diimines (I) to form N-alkyl-4-alkylamino-5-methylenepyrrol-2-ones (II). In turn, these compounds can be easily transformed into tetramic acid derivatives (III) in two additional steps.

Journal Article↗