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Selenothioic acid S-alkyl esters were synthesized from the reaction of terminal acetylenes with n-butyllithium, selenium, and alkanethiols in moderate to high yields. The use of substituted benzenethiols or (triphenylsilyl)acetylene allowed for the isolation of S-aryl esters. The synthesis of α-aryl selenothioic acid S-alkyl esters was attained by the acid-catalyzed reaction of selenoacetic acid Se-alkynyl esters with thiols in good yields. 77Se NMR studies showed that the chemical shifts in a series of the esters were downfield of that in selenoester by about 500 ppm and were upfield of that in selenoketone by about 600 ppm. In the visible spectra the absorptions of the esters were observed at about 340 and 568 nm. X-ray molecular structure analyses of α-silyl esters showed that the bond distances in the selenocarbonyl group were 1.792 and 1.785 Å, respectively. The formation of 1,3-diselenetane was confirmed from the decomposed products of S-phenyl ester. The trend for the stability of selenothioic acid S-esters is discussed on the basis of these synthetic results.

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1996organo-selenium compounds, acyclic C derivatives organo-selenium compounds, acyclic C derivatives S 0132 -172Stereoselective Generation and Trapping of Lithium Eneselenolates Leading to Ketene Selenothioacetals and Selenothioesters.-The reaction of lithium alkyneselenolates generated from terminal acetylenes (I) and (VIII) with thiols (II) and (IX) gives rise to lithium eneselenolates with high stereoselectivity. The trapping with alkyl halides (III) affords ketene selenothioacetals (IV), whereas the trapping with allylic bromides (VI) yields γ,δ-unsaturated selenothioesters (VII) and (X) via seleno-Claisen rearrangement. -(MURAI, T.; KAKAMI, K.; ITOH, N.; KANDA, T.; KATO, S.; Tetrahedron 52 (1996 Tetrahedron 52 ( ) 8, 2839 Tetrahedron 52 ( -2846 Dep. Chem., Fac. Eng., Gifu Univ., Yanagido, Gifu 501-11, Japan; EN)

1998 organo-selenium compounds, acyclic C derivatives organo-selenium compounds, acyclic C derivatives S 0132 -1914-Penteneselenothioic Acid S-Alkyl Esters: Synthesis via the Seleno-Claisen Rearrangement.-Selenothioic acid S-alkyl esters react with allylic bromides to afford mono-, di-, as well as triallylated products selectively by changing amount of allylic bromides and reaction temperature. The reaction proceeds via seleno-Claisen rearrangement and exhibits high regio-and stereoselectivity. However, selective monoallylation of the ester (VII) cannot be observed. Desired monoallylated products are obtained by allylation of the selenolate (XI). -(MURAI, T.; TAKADA, H.; KAKAMI, K.; FUJII, M.; MAEDA, M.; KATO, S.; Tetrahedron 53 (1997) 36, 12237-12247; Dep. Chem., Fac. Eng., Gifu Univ., Yanagido, Gifu 501-11, Japan; EN)