0000000000002989
AUTHOR
Antonio Abad
showing 37 related works from this author
Selective favorskii rearrangement in macrocyclic rings
1981
Abstract A mixture of 2,2-dibromo-12-chlorocyclododecanone (IIa) and 2,12-dibromo-2-chlorocyclododecanone (IIb) by Favorskii rearrangement gave selectively methyl 2-chloro-1-cycloundecene-1-carboxylate (IIIa).
Synthesis of (−)-auricularic acid and its C-4 epimer the absolute configuration of auricularic acid
1991
Abstract A synthesis of (−)-auricularic acid (2a) starting from methyl (+)-13-oxo- podocarp-8(14)-en-19-oate (3a) and a synthesis of its C-4 epimer (2b) starting from methyl (+)-13-oxopodocarp-8(14)-en-18-oate (3b) are described. The absolute configuration of natural auricularic acid is stablished as (4R, 5S, 8S, 9R, 10S, 14S).
Synthesis of (+)-podocarp-8(14)-en-13-one and methyl-(+)-13-oxo-podocarp-8(14)-en-18-oate from abietic acid
1985
Abstract An efficient method for the preparation of (+)-podocarp-8(14)-en-13-one 6 and methyl-(+)-13-oxo-podocarp-8(14)-en-18-oate 8 from abietic acid is described.
Enantioselective Synthesis of Cuparane Sesquiterpenes. Synthesis of (−)-Cuparene and (−)-δ-Cuparenol
1996
(−)-Cuparene and (−)-δ-cuparenol, two cuparane-type sesquiterpenoids, were synthesized from β-cyclogeraniol in 47% and 27% overall yield, respectively, using a Katsuki−Sharpless asymmetric epoxidat...
ChemInform Abstract: Enantioselective Synthesis of Herbertane Sesquiterpenes: Synthesis of (-)-α-Formylherbertenol.
2010
Abstract The synthesis of 4-hydroxy-3-[(1 S )-1,2,2-trimethylcyclopentyl]benzaldehyde [(−)-α-formylherbertenol 1 ], a herbertane-type sesquiterpene isolated from the leafy liverwort Herberta adunca , from β-cyclogeraniol is described. The synthesis is based on the previously described preparation of an enantiopure 1,2,2-trimethylcyclopentane synthon from which the characteristic aromatic moiety of 1 is elaborated, using a Robinson annulation and a palladium-catalysed methoxycarbonylation of an aryl triflate as key synthetic steps. The synthesis of the natural sesquiterpene (−)-α-herbertenol, also a natural sequiterpene, using the same methodology is also described.
Enantioselective Synthesis of Herbertane Sesquiterpenes. Synthesis of (−)-Herbertene and (−)-α-Herbertenol
2001
Stereoselective synthesis of polyoxygenated atisane-type diterpenoids
2001
Abstract A new stereoselective approach to polyoxygenated atisane-type diterpenes starting from (S)-(+)-carvone is described. The key steps involve an intramolecular Diels–Alder reaction, an unusual intramolecular diazo ketone cyclopropanation of an unsaturated ketone, and a regioselective endocyclic cleavage of a cyclopropyl carbinyl radical as key synthetic steps. The synthesis of the bioactive polyoxygenated atisanes atis-16(17)-en-3,14-dione ( 2 ) and 3R-hydroxy-atis-16(17)-en-2,14-dione ( 3 ) following this approach is presented.
The product of a regiospecific and stereoselective ene-reaction of a polycyclic terpenoid system
2001
The X-ray structure of dimethyl (Z)-[(8aS,2R,4aR,4bR)-8a-methoxycarbonyl-1,4a,7-trimethyl-8-oxo-2,3,4,4a,4b,5,8,8a,9,10-decahydrophenanthren-2-yl]-2-butenedioate, C25H32O7, confirmed its relative configuration. The structure shows the bend in the molecular skeleton as found for similar compounds. Weak intermolecular C—H⋯O interactions have been found in the crystal.
Synthesis of oxygenated spongiane-type diterpenoids from carvone
2002
Abstract A new diastereoselective approach to oxygenated spongiane diterpenes starting from ( R )-(−)-carvone is described. The carvone is incorporated as the B ring in the final spongiane framework using a B→AB→ABC→ABCD approach, which involves an intramolecular Diels–Alder reaction and the regioselective ring-opening of a dihydrofuran ring as key synthetic steps. The structure of the key intermediate in this approach has been verified by X-ray crystallography.
Influencia de la edad gestacional en la contractilidad de los vasos coriónicos humanos in vitro
2002
Resumen Los vasos placentarios humanos carecen de inervacion autonoma y, por lo tanto, la resistencia vascular debe ser controlada por factores humorales y mecanismos anteriores autocrinos o paracrinos. Estos factores pueden variar en las diferentes etapas de la gestacion; asimismo, la respuesta de los vasos placentarios puede ser diferente segun la edad gestacional. Se conocen diversas sustancias que, originadas en el feto, la madre o el cordon umbilical, pueden afectar al tono vascular fetoplacentario de forma directa o indirecta. Investigamos si la edad gestacional modifica la respuesta vascular in vitrode los vasos placentarios a unagente vasoconstrictor como el cloruro potasico (ClK).
CONVERSION OF RESIN ACIDS INTO STEROIDAL COMPOUNDS. A REVIEW
1991
(1991). CONVERSION OF RESIN ACIDS INTO STEROIDAL COMPOUNDS. A REVIEW. Organic Preparations and Procedures International: Vol. 23, No. 3, pp. 321-356.
Synthetic studies on the preparation of oxygenated spongiane diterpenes from carvone
2003
Abstract The paper describes a new diastereoselective approach to oxygenated spongiane diterpenes functionally related to natural dorisenones. The strategy followed for the preparation of the spongiane framework, a B→AB→ABC→ABCD approach, is based on the preparation of epoxydecalone 11 (AB rings) from R-(−)-carvone, followed by an intramolecular Diels–Alder reaction for the construction of the C ring (compound 26 ). Further manipulation of the Diels–Alder adduct functionality allows the completion of the spongiane framework and the elaboration of several oxygenated spongiane-type compounds. The structures of two compounds 27 and 31 , has been established by single-crystal X-ray crystallogra…
1H,13C and19F NMR spectroscopy of polyfluorinated ureas. Correlations involving NMR chemical shifts and electronic substituent effects
2005
Seventeen N-(mono-, di-, tri-, tetra- and penta-fluorophenyl)-N′-(3-nitrophenyl)ureas were prepared and characterized. Complete assignment of their 1H, 13C and 19F NMR data was undertaken and the correlation of the chemical shifts of the ureido protons with field-inductive and mesomeric electronic substituent parameters was studied using the Swain–Lupton model. The best correlations were obtained when the study was limited to certain substitution patterns, e.g. non-ortho, mono-ortho- and di-ortho-fluorinated ureas, which reveal probable changes in conformations caused by the degree of ortho fluorination at the phenyl ring. Additionally, there is an excellent linear cross-correlation between…
An approach to erythrophleum alkaloids. Synthesis of methyl (−)-4-epi-cassamate
1986
Abstract A synthetic approach to Erythrophleum alkaloids, involving as a key-step the regiospecific deprotonation of the ketone 5a, is described.
Synthesis of fluorinated drimanes. Preparation of 9αF-drimenin
2003
Abstract A stereoselective approach to the 9α-fluorinated analogue of the natural drimane sesquiterpene drimenin starting from β-ionone is described. β-Ionone is transformed into a bicyclic β-cetoester from which 9αF-drimenin is prepared through stereoselective electrophilic fluorination at the C-9 with N -fluorobenzenesulfonimide followed by Wittig methylenation, allylic bromination, bromine-hydroxyl exchange and γ-lactonization.
Stereostructural revision of auricularic acid synthesis of 4-epi-auricularic acid
1989
Abstract Cleistanth-13,15-dien-18-oic acid (1) has been synthesised from methyl 13-keto-podocarp-8(14)-en-18-oate (3). It is demonstrated that auricularic acid is an epimer at C-4 of 1, so it must be reformulated as cleistanth-13,15-dien-19-oic acid (2).
Preparation and Promotion of Fruit Growth in Kiwifruit of Fluorinated N-Phenyl-N‘-1,2,3-thiadiazol-5-yl Ureas
2004
Seventeen phenyl-fluorinated analogues of thidiazuron [N-phenyl-N'-(1,2,3-thiadiazol-5-yl)urea, TDZ] have been prepared and characterized. The effects of each fluorinated urea on growth and quality of kiwifruits (Actinidia deliciosa) were evaluated by comparison with untreated (control) and TDZ-treated fruits. The results obtained showed a clear dependence of the growth-promoting activity of these fluorinated ureas on the pattern and degree of fluorine substitution in the phenyl ring. The most effective for promoting fruit growth was N-(2,3,5,6-tetrafluorophenyl)-N'-(1',2',3'-thiadiazol-5'-yl)urea at 25 ppm (at harvest, treated fruits were 58% heavier than untreated ones) followed by N-(3,5…
ChemInform Abstract: Synthesis of (-)-Auricularic Acid and its C-4 Epimer. The Absolute Configuration of Auricularic Acid.
2010
Abstract A synthesis of (−)-auricularic acid (2a) starting from methyl (+)-13-oxo- podocarp-8(14)-en-19-oate (3a) and a synthesis of its C-4 epimer (2b) starting from methyl (+)-13-oxopodocarp-8(14)-en-18-oate (3b) are described. The absolute configuration of natural auricularic acid is stablished as (4R, 5S, 8S, 9R, 10S, 14S).
Preparation of 9a-Fluorinated Sesquiterpenic Drimanes and Evaluation of Their Antifeedant Activities
2010
19 pages, figures, and tables statistics.
Isolated human chorionic vascular reactivity: Technical considerations for fresh preparations
1998
1. 1. Sixty chorionic vascular rings from normal term placentas were immersed in an organ bath for isometric tension recording to study (A) the contractile response to 120 mM of potassium chloride (KCI) after adjustment and equilibration to 1–5 g of passive tension; and (B) the concentration-response curve to KCI after adjustment and equilibration to the optimal passive tension. 2. 2. Adjustment to 4 g of passive tension elicited the maximal (P<0.007) and the latest (P<0.006) KCl-induced contraction among arterial rings. Venous rings showed the greatest contraction when adjusted to 3 g, but the differences were not significant except when compared to 1 g of passive tension (P<0.03). 3. 3. T…
An Efficient Stereoselective Synthesis of Stypodiol and Epistypodiol
1998
An efficient synthesis of stypodiol (1) and its epimer at C-14, epistypodiol (2), was accomplished starting from (S)-(+)-carvone (7). The synthesis of both epimeric compounds proceeds through common intermediates using an IMDA reaction, a sonochemical Barbier reaction, and an acid-catalyzed quinol−tertiary alcohol cyclization as key synthetic steps.
Regiospecific and stereoselective ene reaction of the A-ring methylcyclohexene moiety of polycyclic terpenoid systems with dimethyl acetylenedicarbox…
2001
Polycyclic terpenoid compounds with a methylcyclohexene moiety at the A-ring, such as 1 and 7, give a regio- and stereoselective ene reaction when heated at low temperatures with dimethyl acetylenedicarboxylate. The structure and stereochemistry of the compound formed in the case of 1, e.g. 5, is determined by X-ray analysis.
ChemInform Abstract: Stereoselective Construction of the Tetracyclic Scalarane Skeleton from Carvone.
2010
The tetracyclic scalarane skeleton 22 has been constructed from (S)-(+)-carvone using two intramolecular Diels–Alder reactions as key synthetic steps.
ChemInform Abstract: Regiospecific and Stereoselective Ene Reaction of the A-Ring Methylcyclohexene Moiety of Polycyclic Terpenoid Systems with Dimet…
2010
Reactivity of isolated human chorionic vessels: analysis of some influencing variables
2003
The aim of the study was to determine whether 24 h of cold storage of samples, mode of delivery, and gestational age influenced in vitro human chorionic vascular reactivity (35 arteries and 34 veins). The following groups were compared: (i) fresh versus 24-h cold-stored (4 °C in Krebs–Henseleit solution) chorionic vascular rings from normal term placentas, (ii) fresh chorionic vascular rings from normal term placentas obtained after vaginal delivery versus those obtained after elective caesarean section, and (iii) fresh chorionic vascular rings from normal term placentas versus those obtained from preterm deliveries. Isometric recording of the concentration–response curve to KCl (5–120 mM)…
Diastereoselective synthesis of antiquorin and related polyoxygenated atisene-type diterpenes
2007
Abstract A diastereoselective approach to polyoxygenated atisene-type diterpenes starting from (S)-(+)-carvone is described. The key steps used in the preparation of the atisene framework are an intramolecular Diels–Alder reaction, an intramolecular diazoketone cyclopropanation, an endocyclic cyclopropane ring cleavage and the regioselective reduction of an allylic bromide by a low-valent chromium species. The synthesis of natural atisanes antiquorin (1), atis-16-ene-3,14-dione (3), atis-16-ene-2,3,14-trione (8) and 3β-hydroxy-atis-16-ene-2,14-dione (9) following this approach is presented. Also described is the synthesis of 18-hydroxy-atis-16-ene-3,14-dione (5), the structure erroneously a…
A unified synthetic approach to trachylobane-, beyerane-, atisane- and kaurane-type diterpenes
2006
A general synthetic approach to the polycyclic carbon skeleton of biogenetically related trachylobane, beyerane, atisane, and kaurane diterpenes from carvone is described. The skeleton of these diterpenes is prepared from a common intermediate, that is, 25, readily prepared from carvone using an IMDA reaction and an intramolecular diazo ketone cyclopropanation of an unsaturated ketone as key steps. The tetracyclic diterpene ring systems are obtained from this key trachylobane-type intermediate through the regioselective reductive cleavage of the cyclopropane ring, after adequate modification of the functionalization around the tricyclo[3.2.1.02,7]octane moiety.
ChemInform Abstract: Conversion of Resin Acids into Steroidal Compounds. A Review
2010
(1991). CONVERSION OF RESIN ACIDS INTO STEROIDAL COMPOUNDS. A REVIEW. Organic Preparations and Procedures International: Vol. 23, No. 3, pp. 321-356.
Syntheses of oxygenated spongiane diterpenes from carvone. Synthesis of dorisenone C
2005
Abstract The synthesis of dorisenone C, a representative member of the spongiane-type diterpene family, is described. The synthesis follows a B→AB→ABC→ABCD approach and is based on the initial preparation of the previously known hydroxy-aldehyde 14 (AB rings) from R -(−)-carvone, followed by an intramolecular Diels–Alder reaction between an oxygenated diene moiety and an acetylenic dienophile for the construction of the C ring (compound 22 ), and adequate manipulation of the Diels–Alder adduct functionality for completion of the spongiane framework.
ChemInform Abstract: New Route to Herbertanes via a Suzuki Cross-Coupling Reaction: Synthesis of Herbertenediol.
2010
Abstract The synthesis of herbertenediol, a relevant member of the herbertane-type sesquiterpene family, is described. The synthesis is based on a new general approach to this group of sesquiterpenes where the herbertane skeleton is constructed using a Suzuki cross-coupling reaction and a [2,3]-sigmatropic Still–Wittig rearrangement as key synthetic steps.
Synthesis of terpenoid unsaturated 1,4-dialdehydes. Pi-facial selectivity in the Diels-Alder reaction of the 1-vinyl-2-methylcyclohexene moiety of po…
2000
13C nuclear magnetic resonance spectra of several podocarpane and cassane diterpenoids
1990
The 13C NMR spectra of several diterpenic derivatives having the podocarpane and cassane skeleton were recorded and interpreted. The most significant effects due to substituent orientation, B/C ring junction stereochemistry and conformational changes are briefly discussed.
New route to herbertanes via a Suzuki cross-coupling reaction: synthesis of herbertenediol
2001
Abstract The synthesis of herbertenediol, a relevant member of the herbertane-type sesquiterpene family, is described. The synthesis is based on a new general approach to this group of sesquiterpenes where the herbertane skeleton is constructed using a Suzuki cross-coupling reaction and a [2,3]-sigmatropic Still–Wittig rearrangement as key synthetic steps.
Syntheses of Oxygenated Spongiane Diterpenes from Carvone. Synthesis of Dorisenone C.
2005
Abstract The synthesis of dorisenone C, a representative member of the spongiane-type diterpene family, is described. The synthesis follows a B→AB→ABC→ABCD approach and is based on the initial preparation of the previously known hydroxy-aldehyde 14 (AB rings) from R -(−)-carvone, followed by an intramolecular Diels–Alder reaction between an oxygenated diene moiety and an acetylenic dienophile for the construction of the C ring (compound 22 ), and adequate manipulation of the Diels–Alder adduct functionality for completion of the spongiane framework.
Enantioselective synthesis of herbertane sesquiterpenes: synthesis of (−)-α-formylherbertenol
2000
Abstract The synthesis of 4-hydroxy-3-[(1 S )-1,2,2-trimethylcyclopentyl]benzaldehyde [(−)-α-formylherbertenol 1 ], a herbertane-type sesquiterpene isolated from the leafy liverwort Herberta adunca , from β-cyclogeraniol is described. The synthesis is based on the previously described preparation of an enantiopure 1,2,2-trimethylcyclopentane synthon from which the characteristic aromatic moiety of 1 is elaborated, using a Robinson annulation and a palladium-catalysed methoxycarbonylation of an aryl triflate as key synthetic steps. The synthesis of the natural sesquiterpene (−)-α-herbertenol, also a natural sequiterpene, using the same methodology is also described.
Stereoselective construction of the tetracyclic scalarane skeleton from carvone
1999
The tetracyclic scalarane skeleton 22 has been constructed from (S)-(+)-carvone using two intramolecular Diels–Alder reactions as key synthetic steps. Abad Somovilla, Antonio, Antonio.Abad@uv.es ; Agullo Blanes, M Consuelo, Consuelo.Agullo@uv.es ; Cuñat Romero, Ana Carmen, Ana.Cunat@uv.es ; Llosa Blasco, Maria Carmen, Carmen.Llosa@uv.es
CCDC 626412: Experimental Crystal Structure Determination
2017
Related Article: Antonio Abad, Consuelo Agulló, Ana C. Cuñat, Ignacio de Alfonso Marzal, Antonio Gris, Ismael Navarro, Carmen Ramírez de Arellano|2007|Tetrahedron|63|1664|doi:10.1016/j.tet.2006.11.083