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Tomás Torroba

Publications and source records attributed to Tomás Torroba.

11 recordsLinked to original sources
PubMed2006

Synthesis of 3-hydroxy-6-oxo[1,2,4]triazin-1-yl alaninamides, a new class of cyclic dipeptidyl ureas.

Cyclohexyl or benzyl isocyanide, benzoyl-, or 4-methoxybenzoylformic acid and semicarbazones underwent Ugi reactions in methanol for 3 days to give the Ugi adducts, which were then stirred with sodium ethoxide in ethanol for 12 h to give 3-hydroxy-6-oxo[1,2,4]triazin-1-yl alaninamides. The X-ray diffraction structure of the first example showed the tautomer having the proton in the O2 atom that was fixed in the crystal by packing in dimers with a H-bond distance of 1.9 A. Selected [1,2,4]triazines were treated with diazomethane for 12 h to get the O-methyl derivatives. Both hydroxy and O-methyl derivatives obtained by this method constitute a new class of pseudopeptidic [1,2,4]triazines composed of two different amino acids, arylglycine and alanine derivatives, in which the N-terminal arylglycine and the peptidic amide nitrogen atoms are bonded through a urea moiety.

Amides↗
PubMed2005

From cyclopentanone oximes to bis[1,2,3]dithiazolo-s-indacenes, cyclopenta[c][1,2]thiazine, pentathiepino-, tetrathiino-, and thienocyclopenta[1,2,3]dithiazoles as a rich source of new materials.

[Structure: see text]. The 1,5- and 1,7-s-hydrindacenedione dioximes reacted with S2Cl2 and iBu3N to give the first examples of bis[1,2,3]dithiazolo-s-indacenes; one of them was a near-infrared dye. In contrast, the silylated bicyclo[3.3.0]octan-2,6-dione dioxime reacted with S2Cl2 and Et3N to give a bicyclic 4-cyanoethylcyclopenta[1,2,3]dithiazole or, after addition of Li2S, a tricyclic 4-cyanoethyl-5,6-pentathiepinocyclopenta[1,2,3]dithiazole, also obtained from 2-cyanoethylcyclopentanone oxime, S2Cl2, and Hünig's base. In related reactions, 2-oxocyclopentylpropionate oxime gave the expected cyclopenta[1,2,3]dithiazole, in addition to an unexpected cyclopenta[c][1,2]thiazine that showed a reversible reduction wave in its CV at -0.95 V. Ethyl 2-oxocyclopentanecarboxylate oxime reacted with S2Cl2, Hünig's base, and Li2S to give a 5,6-tetrathiinocyclopenta[1,2,3]dithiazole derivative. Cyclopentathiophen-4-one oximes reacted with S2Cl2 and iBu3N to give thienocyclopenta[1,2,3]dithiazoles that showed UV-vis spectral bands that depended on the positions of the ring fusion.

Journal Article↗
PubMed2005

Indene and pseudoazulene discotic liquid crystals: a synthetic and structural study.

Several new liquid-crystalline indene and pseudoazulene systems are reported. These molecules give rise to either columnar hexagonal mesophases and/or columnar plastic phases. The unique nature of these compounds stems from their non-classical discotic structure. Although the molecules have rigid aromatic cores, they lack terminal tails and instead the polarizable atoms (S, halogens) or polar groups (CN, CO) act as unusual soft parts. On the basis of many structurally related materials, we conclude that for this type of compound molecular stacking in the solid state is a prerequisite for the appearance of a columnar mesophase, although other intermolecular interactions within the layers are also important in establishing liquid-crystalline order. The behavior reported for these mesomorphic molecules opens up new possibilities in the search for related molecular interactions that might be useful for the construction of supramolecular architectures with particular properties.

Journal Article↗
PubMed2004

Synthesis of highly branched sulfur-nitrogen heterocycles by cascade cycloadditions of [1,2]dithiolo[1,4]thiazines and [1,2]dithiolopyrroles.

We report the synthesis of some new polysulfur-nitrogen heterocycles by cascade cycloadditions to readily available polycyclic 1,2-dithiole-3-thiones. Thus, treatment of bis[1,2]dithiolopyrrole dithione 1 with dimethyl acetylenedicarboxylate (DMAD) or dibenzoylacetylene (DBA) gave the 1:4 adducts 2a,b and 3a. On the other hand, cycloaddition of bis[1,2]dithiolo[1,4]thiazine dithiones 4a-d with the same dipolarophiles gave the 1:2, 1:3, or 1:4 adducts 5a-c, 6a, 7a, 8a, 9a, and 10a,c,d selectively in fair to high yields. Reaction conditions were crucial for achievement of selectivity in thermal reactions. Catalysis by scandium triflate was used in the reaction of 4a and 2 equiv of DMAD. Treatment of the [1,2]dithiolo[1,4]thiazine dithione 11 with DBA gave the 1:2, 1:3 (two isomers), and 1:4 adducts 12-14 and 15a-d selectively. Cyclic voltammetry of selected examples showed irreversible processes that were not influenced by peripheral groups bonded to the heterocyclic system.

Journal Article↗
PubMed2003

1,4-thiazepines, 1,4-benzothiazepin-5-ones, and 1,4-benzothioxepin orthoamides via multicomponent reactions of isocyanides.

The intramolecular Ugi four-component condensation between 6-oxo-4-thiacarboxylic acids, benzylamines, and cyclohexyl isocyanide gave hexahydro-1,4-thiazepin-5-ones and 1,4-benzothiazepin-5-ones, in some cases with high stereoselectivity, and the intramolecular Passerini three-component reaction, in the presence of catalytic amine, gave tetracyclic 1,4-benzothioxepin orthoamides.

Journal Article↗
PubMed2003

Synthesis, chemistry, and dynamic NMR study of new atropisomeric 4-dialkylamino-5-chloro-1,2-dithiole-3-thiones.

[reaction: see text] Reaction of N-(2-phthalimidoethyl)-N-alkylisopropylamines and S(2)Cl(2) gave atropisomeric (by dynamic NMR) 4-N-(2-phthalimidoethyl)-N-alkylamino-5-chloro-1,2-dithiole-3-thiones that quantitatively cycloadded to dimethyl or diethyl acetylenedicarboxylate to give a novel class of stable thioacid chlorides, which in turn reacted with 1 or 2 equiv of secondary amines to give thioamides.

Journal Article↗
PubMed2002

Synthesis of [1,3]dithiole and spiro[1,3]dithiole thiopyran derivatives of the [1,2]dithiolo[1,4]thiazine ring system.

We report the synthesis of some new polysulfur-nitrogen heterocycles by cycloaddition reactions to readily available tricyclic condensed 1,2-dithiole-3-thiones. Thus, treatment of bis[1,2]dithiolopyrrole ketothione 1 with diacyl acetylenes gave the bis-aducts 2a-d. On the other hand, cycloaddition of bis[1,2]dithiolo[1,4]thiazine ketothione 3 with 1 equiv of acyl or diacyl acetylenes gave [1,3]dithiolylidenyl[1,2]dithiolo[1,4]thiazines 4a-f in fair to high yields. Catalysis by scandium triflate was used in the reactions that implied the less reactive dipolarophiles. Treatment of 3 with 2 equiv of DBA gave the bis-aduct 5a, and reaction of 4c with DMAD gave the mixed bis-adduct 5b. Cyclic voltammetry of selected examples showed irreversible processes that were influenced by the electrochemical activity of peripheral groups bonded to the heterocyclic system.

Journal Article↗