Regioselectivity of nucleophilic addition to conjugated allenic ketones depends strongly on the nucleophile: anionic nucleophiles, e.g., triethylamine salts of benzenethiols, gave the /3-substituted /3,7-unsaturated ketones with high selectivity. In contrast, neutral nucleophile molecules, e.g., benzenethiols or aniline, afforded the ¡3-substituted ,/3-unsaturated ketones. The reactions to allenecarboxylic esters indicated the same regiochemical tendency, but lower selectivities were observed in the reactions with benzenethiol.
Infrared Spectra of Two Peptide Bonds, the Polypeptide Chain 186-3 more remote branching would not be expected to alter the curve appreciably from that of 2-methyl-2•dodecenoic acid. The absence of a 10.1 µ band in the spectrum of 2,5-dimethyl-2-heptadecenoic acid rules out at least one isomeric form of this structure. The available spectra do not provide any basis for a choice from among the other most likely structures.Note added in proof.-Recently a sample of synthetic 2,4-dimethyl-2-dodecenoic acid has become available from Professor Cason,6 and its infrared spectrum has been examined. In the region beyond 10 µ, absorption bands are found at the following wave lengths (values for the corresponding bands of C27-phthienoic acid-see Figs. 3 and 4are given in parentheses for comparison): 10.05 (10.06), 12.3 (12.50), 13.2 (13.26), 14.9 (14.92) µ. Considered together with previous evidence, these data indicate that the second branching methyl group of Cz7-phthienoic acid is in the y-position.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.