Chamamé y humor

Lo más serio del humor es su imposibilidad de definirlo. Ni gracia, ni broma, ni solamente ingenio, ese contrapelo de las cosas, sirve para el ejercicio en trasluz de la mirada del hombre. Algunos lo consideran triste, o tal vez, melancólico resultado de un regreso desde el punto en que antes fuera serio lo que hoy se desconfía que lo sea, al menos en igual medida. Es común que en las fracturas del hombre con sus cosas, el espacio Jibre y sus entresijos, se llenen de humor.

(-)-Isosantonic acid: Alteration of the hydrogen-bonding mode by configurational inversion at a single centre in a γ,ε- diketocarboxylic acid

The title diketo acid, (1R,3aS,6aS,7R,9S)-(-)-α,3a,7-trimethyl-5,8- dioxo-1,4-ethanoperhydropentalene-1-acetic acid (C15H 20O4), is shown to aggregate in the crystal structure as acid-to-ketone hydrogen-bonding catemers, whose chains follow 21 screw axes from each carboxyl to a ketone in a neighbouring molecule [O⋯O = 2.7472(13) and O⋯H - O = 172.7(17)°]. Two parallel counterdirectional screw-related single-strand hydrogen-bonding chains pass through the cell in the a direction. Six intermolecular C - H⋯O=C close contacts are found. Comparisons are drawn with a diastereomer having the opposite configuration at the methylated chiral centre adjacent to the carboxyl group.Fil: Zinczuk, Juan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Química Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario; ArgentinaFil: Ruveda, Edmundo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Química Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario; ArgentinaFil: Lalancette, Roger A.. Rutgers University; Estados UnidosFil: Thompson, Hugh W.. Rutgers University; Estados Unido

C-13 CONFIGURATION OF THE BROMINE-CONTAINING DITERPENE ISOAPLYSIN-20 - SYNTHESIS OF DEBROMOISOAPLYSIN-20 AND ITS C-13 EPIMER

45351051

The C-13 Configuration Of The Bromine-containing Diterpene Isoaplysin-20. Synthesis Of Debromoisoaplysin-20 And Its C-13 Epimer

Syntheses of the tricyclic diterpenes 13-epidebromoisoaplysin-20 (14) and debromoisoaplysin-20 (15) from methyl copalate (3) are described. Methyl isocopalate (4) prepared from 3 was converted into the corresponding alcohol 8. By epoxidation of 8 a 1:1 mixture of isomeric epoxides was obtained; the reductive opening of the α-epoxide (13) afforded 14. Hydroxylation of 4 gave the diol ester 16, which on oxidation with dimethyl sulfoxide-acetic anhydride yielded 18a. Transformation of 18a into the ethylene thioketals 20 and 20a, followed by desulfuration of the mixture to the hydroxy ester 21, and subsequent lithium aluminium hydride reduction afforded 15. The stereochemical features of the epoxides 9 and 13 and the diol ester 16 as well as those at C-13 of 14 and 15 were determined by analysis of their 13C NMR spectra. On the basis of the comparison of the 1H NMR signals of the methyl groups of 14 and 15 and the ones of the acetoxymethylene groups of their monoacetates 14a and 15a with those reported for the methyls of the bromine-containing diterpene isoaplysin-20 (1) and the acetoxymethylene of its monoacetate (1a), the stereochemistry of the natural product was established. © 1980 American Chemical Society.45351051

Lignans Of Araucaria Angustifolia And 13c Nmr Analysis Of Some Phenyltetralin Lignans

Secoisolariciresinol monomethyl ether and lariciresinol-4-methyl ether were isolated from the knots of dead trees of Araucaria angustifolia. On the basis of spectral evidence, the position of the OH group was located in these compounds. The 13C NMR spectra of the phenyltetralin lignans galbulin, galcatin, isogalcatin and cyclogalgravin have also been recorded and the signals assigned, based on the methyl shifts of cyclogalgravin. © 1979.181017031708Fonseca, Campello, Barata, Rúveda, (1978) Phytochemistry, 17, p. 499Anderegg, Rowe, Lignans, the Major Component of Resin fromAraucaria angustifoliaKnots (1974) Holzforschung, 28, p. 171Lüdemann, Nimz, 13C-kernresonanzspektren von ligninen, 2. Buchen- und fichten-björkman-lignin (1974) Die Makromolekulare Chemie, 175, p. 2409Abe, Yahara, Kubo, Nonaka, Okabe, Nishioka, (1974) Chem. Pharm. Bull. (Tokyo), 22, p. 2650Pelter, Stainton, Barber, The mass spectra of oxygen heterocycles (III) . An examination of simple lignans (1966) Journal of Heterocyclic Chemistry, 3, p. 191Pelter, Ward, Venkata, Sastry, (1976) Tetrahedron, 32, p. 2783. , and refs. cited thereinPelter, Ward, Nishino, (1977) Tetrahedron Letters, p. 4137Fonseca, Barata, Rúveda, Baker, 13C nuclear magnetic resonance spectral and conformational analysis of naturally occurring tetrahydrofuran lignans (1979) Canadian Journal of Chemistry, 57, p. 441Gottlieb, (1977) Fortschr. Chem. Org. Naturst., 37, p. 1Birch, Milligan, Smith, Speake, 902. Some stereochemical studies of lignans (1958) Journal of the Chemical Society (Resumed), p. 4471Wenkert, Buckwalter, Burffit, Gasic, Gottlieb, Hagaman, Schell, Wovkulich, (1976) Topics in Carbon-13 NMR Spectroscopy, p. 2. , G.C. Levy, Wiley-Interscience, New YorkWenkert, Cochran, Hagaman, Schell, Neuss, Katner, Kan, Roland, (1973) J. Am. Chem. Soc., 95, p. 4990Wallace, Porte, Hodges, 275. Lignans from Myristica otoba. The structures of hydroxyotobain and iso-otobain (1963) Journal of the Chemical Society (Resumed), p. 1445Buckwalter, Burfitt, Nagel, Wenkert, Näf, (1975) Helv. Chim. Acta, 58, p. 1567Ayres, Harris, Preferred axial conformation of the pendant substituent in 1-aryldihydronaphthalenes and aryltetralones (1969) Journal of the Chemical Society D: Chemical Communications, p. 113

De Iquios a Iquir: los primeros treinta años de quimica en Rosario

La historia reciente de la “Química en Rosario” se inició, sin que nosotros mismos nos diéramos cuenta, a fines de la década del 60 en los laboratorios del Depar- tamento de Química Orgánica de la Facultad de Far- macia y Bioquímica de la Universidad de Buenos Aires...Fil: Kaufman, Teodoro Saul. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Química Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario; ArgentinaFil: Gonzalez Sierra, Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Química Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario; ArgentinaFil: Ruveda, Edmundo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Química Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario; Argentin

STEREOSELECTIVE SYNTHESIS OF THE NOVEL MARINE DITERPENE (+)-ISOAGATHOLACTONE

1573473

C-13 NMR SPECTRAL ANALYSIS OF LIGNANS FROM ARAUCARIA-ANGUSTIFOLIA

17349950