Rangappa Paramashivappa, Shine Henry J, Marx John N, Ould-Ely Teyeb, Kelly Anna T, Whitmire Kenton H
Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409, USA.
J Org Chem. 2005 Nov 25;70(24):9764-70. doi: 10.1021/jo051317q.
[structure: see text] Thianthrene cation radical tetrafluoroborate (Th*+ BF4(-)) added to the terminal alkynes 1-pentyne, 1-hexyne, 1-heptyne, 1-octyne, 1-nonyne, and 1-decyne to form trans-1,2-bis(5-thianthreniumyl)alkene tetrafluoroborates (1-6). Similarly, addition of phenoxathiin cation radical tetrafluoroborate (PO*+ BF4(-)) to the same alkynes gave 1,2-bis(10-phenoxathiiniumyl)alkene tetrafluoroborates (7-12). The trans configuration of two of the adducts (1 and 4) was shown with X-ray crystallography. When solutions of 1-6 in chloroform were stirred with activated alumina, cis elimination of a proton and thianthrene (Th) occurred with the formation of 1-(5-thianthreniumyl)alkyne tetrafluoroborates (1a-6a). Similar treatment of 8-12 caused elimination of a proton and phenoxathiin (PO) with formation of 1-(10-phenoxathiiniumyl)alkene tetrafluoroborates (8a-12a). Stirring of 1a-6a with alumina for short periods of time caused their conversion into 5-[(alpha-keto)alkyl]thianthrenium ylides (1b-6b) and alpha-ketols, RC(O)CH2OH (1c-6c).
[结构：见正文] 将二噻蒽阳离子自由基四氟硼酸盐（Th⁺ BF₄⁻）添加到末端炔烃1-戊炔、1-己炔、1-庚炔、1-辛炔、1-壬炔和1-癸炔中，形成反式-1,2-双（5-噻蒽鎓基）烯烃四氟硼酸盐（1-6）。类似地，将吩恶噻阳离子自由基四氟硼酸盐（PO⁺ BF₄⁻）添加到相同的炔烃中，得到1,2-双（10-吩恶噻鎓基）烯烃四氟硼酸盐（7-12）。通过X射线晶体学确定了两种加合物（1和4）的反式构型。当1-6在氯仿中的溶液与活性氧化铝搅拌时，质子和顺式二噻蒽（Th）发生消除反应，形成1-（5-噻蒽鎓基）炔烃四氟硼酸盐（1a-6a）。对8-12进行类似处理，导致质子和吩恶噻（PO）消除，形成1-（10-吩恶噻鎓基）烯烃四氟硼酸盐（8a-12a）。将1a-6a与氧化铝短时间搅拌，使其转化为5-[(α-酮基)烷基]噻蒽叶立德（1b-6b）和α-酮醇，RC(O)CH₂OH（1c-6c）。
