Showing papers in "Tetrahedron in 1977"

TL;DR: The macrolide class of natural products, although known for some time, has until recently received little synthetic attention as discussed by the authors, mainly due to the lack of general synthetic methodology and the complex structures involved, but in recent years has changed with the development of new experimental techniques.

TL;DR: In this article, a graph theoretical approach based on the concept of conjugated circuits and a semi-empirical variant developed by Herndon is proposed for the analysis of Kekule structures.

TL;DR: In this paper, a critical comparison of the diradical and concerted mechanisms for 1,3-dipolar cycloadditions is given, with references also to the Diels-Alder reaction and Cope rearrangement.

TL;DR: In this paper, the assignment of 13 C NMR signals of fifteen 20-hydroxy-dammarane derivatives including Ginseng sapogenins have been achieved by the aid of shift reagents and deuterated compounds.

TL;DR: In this article, the p K a values of these flavonoids are shown to fit the linear relationships between p K, and substituent σ constant for a series of related phenols.

TL;DR: In this article, the interaction between 1,3-isochromanediones(homophthalic anhydrides) and acyclic azomethines of types 2 and 3 and the cyclic 6,7-dimethoxy-3,4-dihydroisoquinoline was investigated.

TL;DR: In this paper, the Woodward-Katz model is applied to the Diels-Alder reaction and the results are confirmed by Houk et al. They show that the doubting expressed by the authors are groundless and that the overlap integrals in the perturbational treatment are explicity.

TL;DR: In this paper, the enantiomers of diplophyllin were obtained on acid isomerization of isoalantolacetone (IoT) for human epidermoid carcinoma (KB cell culture, ED50⋍ 8 μ g ml ) than its enantiomer.

TL;DR: The absolute stereochemistry of a series of 3-substituted cis-dihydrodiols obtained by microbial oxidation of toluene, ethylbenzene, chlorobenzene, and biphenyl has been assigned from chemical and spectrophotometric studies as discussed by the authors.

TL;DR: In this article, the absolute configuration of (−)-4-methylheptan-3-ol was determined to be 3S,4S. The synthesis of (R)-(+)-Citronellic acid was converted to a mixture of (3R,4R)- (+)-threo- and (3S, 4 R)-( +)-erythro-isomers which was separable by GLC.

TL;DR: In this article, weitgehende Zuordnung der Signale erfolgte mit Hilfe der geminalen und vicinalen 13C-1H-Kopplungen und den Substituenteneffekten.

TL;DR: In this paper, the contribution of the rings to the total π-electron energy (CE) of polycyclic conjugated hydrocarbons is calculated for the Huckel 4m+2 rule.

TL;DR: In this paper, force field calculations have been extended to include carboxylic acids and esters, with necessary parameters chosen mainly by fitting to available experimental data on small molecules.

TL;DR: In this article, 1-trimethylsilyl-1-alkynes with dicyclohexylborane was shown to yield (Z )-1,2-dialkylvinylsilanes in high yields.

TL;DR: In this paper, the synthesis of the methyl esters of N -methoxycarbonyl- and N -benzyloxy carbonylaziridine-2-carboxylic acid by reacting methyl 2-chloro- N -carbalkoxyglycinate 1 with diazomethane is described.

TL;DR: In this paper, the structure of the colorless dimer, which is of a type not previously reported, suggests that an ionic reaction is involved in its formation, which rapidly dimerises in polar solvents.

TL;DR: In this article, the conformational energy of N-methylpiperidine has been determined in the gas phase (ΔG°288 ⋍ 13.2 ± 0.4 kJ mol−1) and for dilute solutions in several solvents (ΓG°293 ranging from 12.5 ± 1.4 in dodecane to 10.1 ± 0.4 in chloroform) by kinetically controlled protonation of anancomeric model compounds 6 and 8 at the interface between the pipendine-containing phase and