Showing papers in "Tetrahedron in 1959"

TL;DR: In this article, the structural elucidation and biosynthesis of brevianamides-A and -E were discussed, and they were shown to be biogenetically derived from tryptophan, proline and mevalonic acid.

TL;DR: In this paper, a modification of the simple molecular orbital theory has been successfully applied to the treatment of ionization potentials of unsaturated molecules, and the best results were obtained for a model in which the methyl group is treated as a single "heteroatom" which donates two electrons to the φ system.

TL;DR: In this article, a mixture of the two specimens afforded a racemate of higher melting point, which was identical with the natural product from Iridomyrmex nitidus.

TL;DR: In this paper, alcoholic hydroxyl groups were methylated by diazomethane in the presence of catalytic amounts of fluoboric acid (FBA), and the new methylation reaction was used to prepare directly methyl ethers of desoxycorticosterone and of testosterone and to convert ascorbic acid selectively to its 2:3:6-trimethyl ether.

TL;DR: In this paper, the effect of terminal groups of absorbing (conjugated) systems on the corresponding K-bands is extended to groups containing multiple bonds, based on the consideration of the electronic perturbations in the excited state (due to Heisenberg resonance) and the view that organic molecules are built up of localised bonds and involve inductive electron shifts only.

TL;DR: In this article, the desirability of an explicit classification of both conjugation and hyperconjugation into two major types, isovalent and sacrificial, is emphasized.

TL;DR: A review of selective reactions and modifications for the partial and total synthesis of steroids can be found in this paper, with a focus on tricyclic intermediates in total synthesis.

TL;DR: In this article, the rate determining stage in the Bamford-Stevens reaction is shown to be a unimolecular elimination from the anion of the sulphonylhydrazone.

TL;DR: In this article, the biosyntheses of rosenonolactone in Trichothecium roseum and of gibberellic acid in Gibberella fujikuroi have been studied by feeding experiments with CH 3 14 CO 2 Na and (2- 14 C)-mevalonic lactone.

TL;DR: The present state of knowledge of the biosynthesis of cholesterol is summarised and a special application of the carbon isotope 13 C permits a decision between possible modes of rearrangement during the enzymic cyclisation of squalene.

TL;DR: In this article, the extent of hydrogen bonding between hydroxyl groups and ring oxygens, as determined by infra-red spectroscopy in the hydrastic stretching region, in a series of monohydroxy derivatives of tetrahydropyran, tetrahedrofuran and 1:3-dioxan, was investigated.

TL;DR: In this paper, the effects of para-alkyl groups (Me, Et, Pr i, Bu t ) in diverse reactivities of benzene derivatives are evaluated by using the inductive reaction constants, π I, obtained in previous work with groups such as NO 2, CN, OCH 3 and halogens.

TL;DR: In this article, the photolysis of diazomethane in 2-methylpropene-1-14 C leads predominantly to 2methylbut-1 -ene, whether the reaction be run in the liquid or gas-phase.

TL;DR: In this article, it was shown that polystictin is 1-carboxy-2-amino-9-hydroxymethylphenoxazin-3-one.

TL;DR: The left colleterial glands of two species of cockroach secrete a β-glucoside of protocatechuic acid, which can be identified readily by chromatography and ultra-violet spectroscopy as discussed by the authors.

TL;DR: In this article, the rotations and configurations of 18 optically active deuterium compounds are summarized and the relative configurations of each alcohol were established by converting each to 1-phenylbutane-1-d using reactions of known or presumed stereochemistry.

TL;DR: In this article, it was shown that the secondary isotope rate effect is paralleled by an isotope activation energy effect, although entropy factors also contribute, and that hyperconjugation is the predominant cause of these secondary ISR effects.

TL;DR: In this article, the structure 2-benzyloxy-6:7-benzo-3-aza bicyclo [3.2.2] nona-8-diene-4-one was assigned to (I) by degradative and analytical methods and independent synthesis.

TL;DR: Application of this method led to the synthesis of 6α-fluorotestosterone and the 6α and 6β-fluoro analogs of progesterone desoxycorticosterone acetate and Reichstein's Compound “S” diacetate.

TL;DR: In this article, a method for degrading boron compounds is described, and also the synthesis of 2-, 6-, and 8-chloro-10-methyl-10:9-borazarophenanthrenes as reference compounds.

TL;DR: In this paper, the spectral evidence for substitution of 9-hydroxyperinaphthenones with atrovenetin has been investigated and the constitutions of these compounds and their transformation products have been elucidated.

TL;DR: The constitution of Albigenic acid, a triterpenoid sapogenin from the beans of Albizzia lebbeck Benth, has been established as 3β:16α-dihydroxyolean-13(18)-en-28-oic acid and its partial synthesis from echionocystic acid is described.

TL;DR: In this paper, allgemein anwendbare Synthesen berichtet, die zum d, l -Iridomyrmecin und ihm verwandter bicyclisher γ- and δ-Lactone fuhren.

TL;DR: In this article, a number of substituted barbituric acids have been found to exist in polymorphic forms, including butethal, amobarbital and kemithal, and these are divided into two groups on the basis of their infra-red spectra.

TL;DR: A new lignan for which the name seco-isolariciresinol is proposed, has been isolated from the heartwood of Podocarpus spicatus as mentioned in this paper, whose structure has been shown to be 2:3-bis(4′-hydroxy-3′- methoxybenzyl)-butan-1:4-diol (II, R = H).

TL;DR: The existing knowledge concerning the gas phase reactions of ions with molecules is summarized in terms of the identification of the reactions, the rate constants of reactions, and the energetic properties of the ions observed to be formed and of those inferred as intermediates as mentioned in this paper.