reported herein gave spectral data in full accord with the assigned structures. New compounds which were sufficiently stable to allow for full characterization gave satisfactory elemental analyses and/or molecular weight measurements (high resolution mass spectrometry). 17) G. H. Posner, D. J. Brunelle, L. Sinoway, Synthesis 1974, 662. (81 In the case of [(6a)-(6d)], silyl enol ether formation was highly regioselective [exclusive or nearly exclusive formation of (70)-(7d)].-When lithium 2.2.6.6-tetramethylpiperidide was used as a base in the place of lithium diisopropylamide, (10) was formed as the major product.191 For studies related to the thermal rearrangement of methylene(viny1)cyclopropane systems, see also W E.
The 1 -pyridinio-4-pyridone cations (1 ) give with aqueous sodium cyanide mixtures of 2-and 4-cyanopyridines, 2-cyanopyridine formation being favoured by high cyanide ion concentration, and 4-cyanopyridine formation by low cyanide ion concentration, when small amounts of the intermediate 1,4-dihydr0-4-cyano-adducts (7) or ( 9) are also observed. The 2,6-dimethyl-1 -pyridinio-4-pyridone cations (2) in contrast give high yields of the 1,4dihydro-4-cyano-adducts ( 8) or (1 0), the former being decomposed quantitatively by heat to 4-cyanopyridines and 2,6-dimethyl-4-pyridone. Only very small amounts of 2-cyanopyridines are formed. Mechanisms for the two reactions are proposed which account for the experimental observations.
Thiolate ions add regiospecifically to N-(4-oxopyridin-l -yl)pyridinium salts (2)-(7) to give in good to excellent yields only the 1,4-dihydropyridine adducts (8)-(13), regardless of whether or not the pyridone moiety carries substituents for sterically shielding the 2and 6-positions of the pyridinium ring. The addition is believed to be thermodynamically controlled. Decomposition of the dihydro-adducts under free-radical conditions, or by pyrolysis, gives good yields of pyridin-4-yl thioethers (1 4) and (1 6) though the reaction failed with the 2-methyl adducts ( 9). An improved synthesis of 6-methyl-4-oxopyran-2-carboxylic acid is also described.
A series of unsaturated secondary amines have been isolated from the dolichoderine antTechnomyrmex albipes (F. Smith). The major components of the mixture have been shown by spectroscopic procedures to be dinon-8-enylamine, andN-hept-6-enylnon-8-enamine, and these structural assignments have been confirmed by synthesis. Mass spectrometry indicates the presence of trace amounts of the bis C11 amine and the C9-C11 amine. The four amines, present in total at approximately 2.8μg/ant, are located in the gaster of the insect in a gland that is considered to be the venom gland although it is atypical from a morphological standpoint.
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