109142-66-7Relevant academic research and scientific papers
Photolysis of Tetraalkyl-1-pyrazoline-4-thiones. - Diastereoselective Formation of (E)/(Z)-Alkylidenethiiranes from cis- and trans-Tetraalkyl-1-pyrazoline-4-thiones
Quast, Helmut,Fuss, Andreas,Jakobi, Harald
, p. 1747 - 1755 (2007/10/02)
The tetraalkyl-1-pyrazolin-4-ones 5 react with hydrazine to afford the hydrazones 6 which are transformed into the thiones 7 in high yields by treatment with disulphur dichloride in the presence of triethylamine.Selective excitation of the azo chromophor of 7a with 350-nm light gives rise to the isopropylidenethiirane 8, besides molecular nitrogen, in a very clean reaction; at almost quantitative conversions, less than 2percent of byproducts are observed, and about 10percent of 8 have isomerized to the pentadienethiol 9.Photolysis of the stereoisomers cis- and trans-7b yields mixtures of the alkylidenethiiranes (E)- and (Z)-10 with (E)/(Z) ratios of 35:65 and 49:51.The results are interpreted in terms of diastereomeric bis-orthogonal (cis- and trans-21) and mono-orthogonal thioxyallyl diradicals (E)- and (Z)-23 which cyclize to furnish (E)- and (Z)-10.There seems to be a qualitative resemblance between the photochemical and thermal stabilities in the series of 4-substituted tetramethyl-1-pyrazolines, viz. 7a oct-2-ene derivatives. Key Words: 4H-Pyrazole-4-thiones, 3,3,5,5-tetraalkyl-3,5-dihydro- / Thiiranes, 3,3-dialkyl-2-alkylidene/ 1,3-Pentadiene-3-thiol, 2,4-dimethyl- / Photolysis/ Extrusion of molecular nitrogen/ (E)/(Z) Stereoselectivity
NATURE OF THYOXYALLYL INTERMEDIATE IN THE DECOMPOSITION OF ALLENE EPISULFIDE AND PYRAZOLINE-4-THIONE
Furuhata, Toshiya,Ando, Wataru
, p. 5301 - 5308 (2007/10/02)
Thermolysis of tetramethylallene episulfide (10) gave 2,4-dimethyl-3-mercaptopenta-1,3-diene(12) via thioxyallyl intermediate(13) by unimolecular C-S bond cleavage. 3,3,5,5-Tetramethylpyrazoline-4-thione(11) also gave 12 probably via the same intermediate(13), which has a biradical character.
