Showing papers in "Tetrahedron in 1993"

TL;DR: In this article, the natural products chemistry of the red alga Delisea pulchra, collected from the Cape Banks, New South Wales, Australia, yielded eight new polyhalogenated furanones ( 1−7 ) and the previously reported metabolites 8−24 ).

TL;DR: In this article, reactions of N,N-dimethylformamide and N-methylformanilide with pyrophosphoryl chloride lead to the formation of reagents that undergo reactions with a wide range of nucleophilic aromatic substrates, including indoles, pyrroles, thiophenes, furans, and methoxy-substituted carbocyclic arenes.

TL;DR: Carboxylic acids react readily at O°→+24°C with amino alcohols, amino mercaptans and o-aminophenols in the presence of triphenylphosphine-or tributyl phosphine dichloride (generated in situ from the reaction of the phosphines with hexachloroethane or CCl4) as discussed by the authors.

TL;DR: In this article, the self-initiated oxidation of β-carotene with molecular oxygen was shown to depend on the oxygen partial pressure, and the main products in the early stage of the oxidation were shown to be 5,6-epoxy-β-Carotene.

TL;DR: Intensive Study of the cell growth inhibition and antineoplastic constituents of the sea hare Dolabella auricularia provided the structurally unique peptides designated dolastatins 1-15, which represents the largest scale separation ofSea hare components.

TL;DR: The design, synthesis and incorporation into bioactive peptides of BTD will be mentioned and the biological activity of the BTD containing peptides and synthesis of some BTD derivatives will also be described.

TL;DR: New convergent synthesis of azacarbazoles through metalation, cross-coupling reaction and intramolecular substitution via (2-aminobenzene)boronic acid and ortho-fluoroiodopyridines as discussed by the authors.

TL;DR: In this paper, an efficient asymmetric aza-Diels-Alder reaction using chiral boron mediator is developed using α-benzylamine as a chiral auxiliary.

TL;DR: In this article, the synthesis of 2-substituted chromones and quinolones has been performed by a Pd-catalyzed carbonylation of oiodophenols or o-iodoanilines in the presence of terminal acetylenes.

TL;DR: In this article, the nucleophilic ring opening of optically active N-sulphonyl aziridine-2-carboxylate esters with organometallic reagents has been investigated as a method of preparation of amino acids.

TL;DR: The topography of the β-turn was investigated in this paper using 146 examples of βturns reported in the literature and common topographical features were observed across a wide variety of β turn types, including the spatial relationship between the entry and exit peptide bonds and the relative orientations of the intervening sidechains.

TL;DR: The ascidian Clavelina cylindrica has yielded two novel alkaloids, cylindricine A, rel-(3R, 4R, 5S, 7aR, 11aR)-3-chloromethyl-5-hexyl-perhydro-pyrrolo-[2, 1-j]quinolin-7-one, (12).

TL;DR: The conformations of the antimitotic agent taxol and its side chain methyl ester have been studied by NMR-spectroscopy and molecular modeling in hydrophobic (CDCl3) and hydrophilic (water, d6-DMSO) solvents as mentioned in this paper.

TL;DR: In this paper, the authors show specificities of microwave heating in terms of reactivity associated with control of very fast heating rate, which is used to control isomeric ratio in sulfonation of naphtalene.

TL;DR: In this article, the trifluoromethyl group acts as the enantiocontrolling larger group as compared to the aryl or alkyl group, and the steric and electronic influence of the triplastic group in achieving enanti-control in asymmetric reductions is discussed.