The influence of substituents on preparation and tautomerism of open-chain β-thioketoesters
作者:F. Duus
DOI:10.1016/0040-4020(72)88125-0
日期:1972.1
the synthesis of β-thioketoesters, the acid catalysed reactions of 36 differently substituted β-keto esters with H2S have been studied under various conditions in order to determine the influence of the substituents on reaction course. gem-Dithiols may also be obtained in good yields by this reaction. Treatment of T1(I)-salts of β-thioketo esters with alkyl halides results exclusively in S-alkylation
Reaction of 1,2-dithiolan- and 1,2-dithiolen-3-ones with phosphines
作者:T. P. Vasil'eva、V. M. Bystrova、M. G. Lin'kova、O. V. Kil'disheva、I. L. Knunyants
DOI:10.1007/bf01418003
日期:1981.7
Determination of tautomeric phenotypes of β-thioxo esters and characterization of the tautomeric enethiolic constituents by means of13C NMR spectroscopy
作者:F. Duus、P. E. Hansen
DOI:10.1002/mrc.1270220105
日期:1984.1
AbstractThe 13C NMR spectra of 28 enethiolizable β‐thioxo esters and 6 enethiolizable β‐thioxo thioloesters have been recorded in order to establish the tautomeric phenotypes of these compounds. All compounds investigated are essentially enethiolic. The carbonyl‐conjugated (Z)‐enethiol form is the exclusive or predominant tautomer of open‐chain β‐thioxo esters and thioloesters, thioacylmalonates and medium‐sized 2‐alkoxycarbonylcycloalkanethiones. The carbonyl‐conjugated (E)‐enethiol form is identifiable for open‐chain α‐unsubstituted β‐thioxo esters and thioloesters, and abundant for open‐chain α‐substituted β‐thioxo esters. Non‐conjugated enethiol forms [i.e. (Z)‐ and (E)‐isomeric β,γ‐unsaturated β‐mercapto esters] are abundant tautomeric constituents of ω‐substituted and higher 2‐alkoxycarbonylcycloalkanethiones. The chemical shifts of the carbon atoms directly involved in the tautomeric change have been rationalized in terms of substituent screening contributions. Deuterium isotope effects on the central carbon atoms of selected deuterio‐enethiolic compounds have been measured in order to depict the ester group rotamerism in CO‐conjugated (Z)‐enethiols. The abundance of the CO‐conjugated (E)‐enethiols, as well as the preferred population of the non‐conjugated (Z)‐enethiol form relative to the non‐conjugated (E)‐enethiol form, is rationalized in terms of the occurrence of a no‐bond interaction between the lone‐pair electrons of the enethiolic sulphur atom and the ‘chelating’ methylene hydrogen atoms of cis‐alkyl groups.