Juan C. Estévez

Synthesis of tetrahydropyrans from sugar lactones

Abstract Dehydration of both γ- and δ- hexonolactones, either by intramolecular nucleophilic displacement of triflate leaving groups at C-2, or by Mitsunobu type displacement of the OH-6, provides access to bicyclic lactones which contain tetrahydropyran rings. Reduction or nucleophilic ring opening of these bicyclic lactones furnishes polyfunctionalised tetrahydropyrans in good yield.

SPIROCYCLIC PEPTIDES AT THE ANOMERIC POSITION OF MANNOFURANOSE

Abstract The first syntheses of two diketopiperazine peptides containing an α-amino in which the α-carbon is also the anomeric carbon of a carbohydrate are described; studies on the kinetic and thermodynamic stability of the spirocyclic dipeptides are reported.

Tri- and tetra-peptides incorporating an α-amino acid at the anomeric position of mannofuranose

Abstract The first examples of peptides containing an α-amino acid residue in which the α-carbon is also the anomeric position of a carbohydrate are described.

Spirodiketopiperazines of mannofuranose: carbopeptoid α-amino acid esters at the anomeric position of mannofuranose

Abstract Epimeric mannofuranose anomeric aminoesters are prepared from readily available azidolactones and can act as building blocks for the incorporation of mannofuranose units into peptide chains [carbopeptoids]; alternative acylating conditions allow either rapid acylation of the more stable but kinetically hindered amine or reaction with the less hindered but less stable amine to allow control of the anomeric configuration of the products. This is exemplified by coupling of the aminoesters with glycine derivatives to give dipeptide equivalents, and subsequent cyclization to spiro diketopiperazines. Anomers with the nitrogen function cis to the 2,3-diol are more stable than those with nitrogen trans ; mannofuranose derivatives are more stable than the mannopyranose isomers.

Mimics of l-rhamnose: Anomeric spirohydantoins and diketopiperazines-approaches to novel N-linked glycopeptides of rhamnofuranose

Abstract An α-azidocarboxylate of a tetrahydrofuran derived from l -rhamnose may be used as a divergent intermediate for a wide range of mimics of l -rhamnofuranose, which contain a constituent α-amino acid moiety at the anomeric position, and include anomeric spiroderivatives such as the rhamnose analogue of hydantocidin; such materials may be helpful in elucidating the biosynthesis of the cells walls of mycobacteria.

Palladium-catalyzed synthesis of o-acetylbenzoic acids: a new, efficient general route to 2-hydroxy-3-phenyl-1,4-naphthoquinones and indolo[2,3-b]naphthalene-6,11-diones

Abstract We describe here a new, efficient general synthesis of o -acetylbenzoic acids by Heck palladium-catalyzed arylation of n -butyl vinyl ether with o -bromobenzoic acid esters and the use of these compounds as starting materials for the synthesis of 3-benzylideneisochroman-1,4-diones, which readily rearrange to 2-hydroxy-3-phenyl-1,4-naphthoquinones. The application of this strategy to the synthesis of indolo[2,3- b ]naphthalene-6,11-diones is also described.

Mimics of l-rhamnose: Analogues of rhamnopyranose containing a constituent α-amino acid at the anomeric position. A rhamnopyranose analogue of hydantocidin

Abstract Ionic brominative oxidation of 2-amino derivatives of protected heptonolactones derived from L-rhamnose provides a key bicyclic intermediate for the synthesis of analogues of L-rhamnopyranose with spirohydantoins and spirodiketopiperazines at the anomeric position; the same intermediate can be used for the synthesis of novel glycopeptides containing a constituent rhamnopyranose amino acid. Such materials may allow an approach to new studies of diseases induced by mycobacteria, such as tuberculosis and leprosy.

A new, simple, efficient synthesis of benzo[b]carbazoles and indeno[1,2-b]indoles

Abstract A new, efficient synthesis of benzo[b]carbazoles and indeno[1,2-b]indoles from nitrophenylacetylphenylacetic acids and nitrobenzylphthalides respectively is described.

Heck-mediated synthesis and photochemically induced cyclization of [2-(2-styrylphenyl)ethyl]carbamic acid ethyl esters and 2-styryl-benzoic acid methyl esters: total synthesis of naphtho[2,1f]isoquinolines (2-azachrysenes) ☆

Abstract We describe two new closely related total syntheses of naphtho[2,1-f]isoquinolines. The first synthesis consists of a Heck coupling reaction between trifluoromethanesulfonic acid 2-(2-ethoxycarbonylaminoethyl)phenyl esters and styrenes to give [2-(2-styrylphenyl)ethyl]carbamic acid ethyl esters. These compounds cyclize to give (2-phenanthren-1-yl-ethyl)carbamic acid ethyl esters, from which 2-azachrysenes can be obtained in a three-step sequence. The second synthesis includes a new total synthesis of 2-styrylbenzoic acid methyl esters by Heck coupling of methyl o-iodobenzoates to styrenes, followed by the transformation of the resulting benzoic acid derivatives into phenanthrene-1-carboxylic acid methyl esters and then into the target compounds by a six-step sequence including a Bischler–Napieralski cyclization.

Synthesis of polyhydroxylated α-nitrocyclohexane carboxylic acids derived from D-glucose: a striking case of racemization

The first total synthesis of polyhydroxylated α-nitrocyclohexane carboxylic acids from sugars is reported. A salient aspect of the synthesis is an unexpected Henry-mediated racemization of this new class of highly functionalized cyclohexanes.