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Biomedical subjects

S Hernández-Ortega

Publications and source records attributed to S Hernández-Ortega.

6 recordsLinked to original sources
PubMed2001

Diethyl 2-[cyano(toluene-4-sulfinyl)methylene]propanedioate and its Diels-Alder adduct with cyclopentadiene.

The thermal Diels-Alder cycloadditon reaction of diethyl 2-[cyano(toluene-4-sulfinyl)methylene]propanedioate, C(16)H(17)NO(5)S, with cyclopentadiene gave the pure racemates of two of the four possible diastereomers, with a complete pi-facial selectivity and a high (80:20) endo/exo-sulfinyl selectivity. X-ray diffraction studies of diethyl 2-[cyano(toluene-4-sulfinyl)methylene]propanedioate and the major isomer of the cycloaddition product, namely diethyl 3-cyano-3-(toluene-4-sulfinyl)bicyclo[2.2.1]hepta-5-ene-2,2-dicarboxylate, C(21)H(23)NO(5)S, reveal that the conformation of the substituents on the acrylonitrile moiety produces both steric and electronic effects, which affect the stereoselectivity of the reaction.

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PubMed2001

2,9-bis(3-nitrophenyl)-1-azaadamantan-4-one.

The title compound, 2,9-bis(3-nitrophenyl)-1-azatricyclo[3.3.1.1(3,7)]decan-4-one, C21H19N3O5, has a tricyclic structure. The torsion angles may be used to describe the relationship of the carbonyl group to the adjacent faces, whereby it is seen that the angles on the face of the arylpiperidinone side [122.0 (3) and -122.0 (3) degrees ] are greater than those on the cyclohexanone side [-119.8 (4) and 119.9 (4) degrees ]. Although these differences may explain a facial selectivity during nucleophilic addition to the carbonyl group, the presence of the aryl rings is probably also important.

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PubMed2001

(C-rac-5,5,7,12,12,14-Hexamethyl-1,4,8,11-tetraazacyclotetradecane-kappa4N)(nicotinato-O,O')nickel(II) perchlorate.

In the title compound, [Ni(C(6)H(4)NO(2))(C(16)H(36)N(4))]ClO(4), the macrocyclic unit adopts a folded conformation, allowing the two carboxyl O atoms to occupy two neighbouring coordination sites and thus form an additional four-membered chelate ring. The less crowded side of the macrocycle (that with the two asymmetric C-H groups) is directed towards the nicotinate anion and the asymmetric C-CH(3) groups are directed away from it. The macrocyclic NH groups neighbouring the C-CH(3) groups are also directed away from the nicotinate anion, while those NH groups which are near to the geminal methyl groups are directed towards the nicotinate anion. Although the complex does not include water molecules, three types of hydrogen bond were found, involving NH groups of the macrocyclic ligand, pyridine N atoms and O atoms of the perchlorate anions.

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PubMed2001

4-Ethoxycarbonyl-3-hydroxy-3-phenylcyclohexanone.

The title compound, ethyl 2-hydroxy-4-oxo-2-phenylcyclohexanecarboxylate, C(15)H(18)O(4), was obtained by a Michael-Aldol condensation and has the cyclohexanone in a chair conformation. The attached hydroxy, ethoxycarbonyl and phenyl groups are disposed in beta-axial, beta-equatorial and alpha-equatorial configurations, respectively. An intermolecular hydrogen bond, with an O.O distance of 2.874 (2) A, links the OH group and the ring carbonyl. Weak intermolecular C-H.O=C (ester and ketone), O-H.O=C (ketone) and C-H.OH hydrogen bonds exist.

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PubMed2000

Formation of a novel trinuclear spirostannoxane tin(IV) compound. Crystal and molecular structure of [Sn(nBu)(Cl)[(OCH2CH2S)2Sn(nBu)]2] and the stannolane [(nBu)Sn(SCH2CH2O)SCH2CH2OH].

The reaction of nBuSnCl3 and the sodium salt of 2-mercaptoethanol (1:1) in ethanol gave the compound Sn(nBu)(Cl)[(OCH2CH2S)2Sn(nBu)]2 (1). [(nBu)Sn(SCH2CH2O)SCH2CH2OH] (2) was initially isolated from the reaction of 1 with nBuMgCl as a rearrangement product but was also synthesized from nBuSn(O)OH and two molar equivalents of 2-mercaptoethanol. Both compounds were characterized by means of IR, 119Sn, 13C, and 1H NMR, FAB mass spectroscopy, and elemental analyses. The structures were determined by single-crystal X-ray diffraction. 1 crystallizes in the monoclinic Cc space group (a = 18.492(3) A, b = 17.329(2) A, c = 10.787(1) A, beta = 111.88(1) degrees, Z = 4), while 2 crystallizes in the orthorhombic Pbca space group (a = 14.458(2) A, b = 10.393(1) A, c = 16.479(2) A, Z = 8). 1 is a trimetallic Tin(IV) compound in which the central atom is in 6-fold coordination, while the two remaining tin atoms show 5-fold coordination. Both pentacoordinated tin atoms are bonded to a butyl group and to the oxygen and the sulfur atoms from two [OCH2CH2S]2- ligands forming two stannolanes, which are fused with the hexacoordinated tin atom forming a distannoxane system. This arrangement is quite different from previous ladder or staircase structures. NMR data point to maintenance of this structure in solution. 2 consists of [(nBu)Sn(SCH2CH2O)(SCH2CH2OH)] units, which are associated via intermolecular Sn-O interactions building up a dimer. The tin atom forms two "stannolane" units by interaction with [OCH2CH2S]2- and [HOCH2CH2S]- ligands.

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