95096-10-9Relevant academic research and scientific papers
Lawesson's reagent for direct thionation of hydroxamic acids: Substituent effects on LR reactivity
Przychodzen, Witold
, p. 676 - 684 (2007/10/03)
To explore the generality and scope of direct thionation of hydroxamic acids (HAs), the reaction of various structurally diverse HAs with Lawesson's reagent was investigated. The yield of thiohydroxamic acid (THAs) is poor when HAs possess bulky acyl and/or N-substituents, acidic α-hydrogen atoms, or an N-phenyl ring. THAs yields were correlated with Brown sigma parameter. The relative rates of two subsequent processes kT2 and kR2 were also measured. Correlation was also found for methine proton chemical shifts of N-isopropyl benzothiohydroxamic acids.
Thioimidate N-Oxides: Nitrones of Thio Esters
Coates, Robert M.,Firsan, Sharbil J.
, p. 5198 - 5209 (2007/10/02)
A group of three C-phenyl and three C-alkyl thioimidate N-oxides (nitrones of thio esters) was prepared by S-alkylation of N-alkylthiohydroxamic acids with methyl or ethyl iodide followed by basification of the resulting hydroiodide salts.An X-ray crystallographic analysis of S-methyl N-Methylthiobenzimidate N-oxide (9Z) established the Z stereochemistry for the more stable isomer.The 1H NMR, 13C NMR, IR, and UV spectral properties of the thio ester nitrones are reported.The E/Z stereochemistry of the C-alkyl derivatives is tentatively assigned on the basis of NOE measurements, long-range coupling, and chemical shift correlations.Thermal equilibration in bromobenzene-d5 at 80 deg C gave the following E/Z ratios: C-phenyl, 5:95; C-methyl, 46:54; C-ethyl, 53:47; C-isopropyl, 83:17.The equilibrium values are rationalized in terms of a balance between electronic stabilization and steric destabilization of the Z isomers.Hydrolysis of 9Z in aqueous acid at 100 deg C gave S-methyl thiobenzoate and N-methylhydroxylamine, whereas basic hydrolysis at 100 deg C afforded N-methylbenzohydroxamic acid as the principal initial product.
