Room-Temperature Metallation of 2-Substituted 1,3-Dithiane Derivatives and Subsequent Coupling with 2,3-Disubstituted Oxiranes
作者:Mitsuaki Ide、Masaya Nakata
DOI:10.1246/bcsj.72.2491
日期:1999.11
2-Substituted 1,3-dithiane derivatives, (S)-1-(t-butyldiphenylsiloxy)-2-(1,3-dithian-2-yl)propane (9), (S)-1-(t-butyldimethylsiloxy)-2-(1,3-dithian-2-yl)propane, 1-(t-butyldiphenylsiloxy)-2-(1,3-dithian-2-yl)-2-methylpropane, and 1,2-bis(t-butyldiphenylsiloxy)-3-(1,3-dithian-2-yl)propane, were subjected to lithiation in THF with n-BuLi at room temperature (r.t.); the resulting anions reacted with 2,3-disubstituted oxirane, trans-2-methyl-3-(triphenylmethoxymethyl)oxirane (22), at r.t., giving the coupling products in satisfactory yield. On the other hand, the lithium salt formed in ether from (S)-2-(1,3-dithian-2-yl)-1-(4-methoxybenzyloxy)propane with n-BuLi at r.t. reacted with 22 at r.t. in the presence of hexamethylphosphoric triamide to afford the coupling product in moderate yield. In addition, a mixed organometallic reagent, n-BuLi / Bu2Mg, was found to be an effective metallation reagent for 9 and the resulting anion reacted with 22 to afford the coupling product in good yield.
2-取代的 1,3-二噻烷衍生物、(S)-1-(叔丁基二苯基硅氧基)-2-(1,3-二噻烷-2-基)丙烷 (9)、(S)-1-(叔丁基二甲基硅氧基)-2-(1,3-二噻烷-2-基)丙烷、1-(叔丁基二苯基硅氧基)-2-(1、和 1,2-双(叔丁基二苯基硅氧基)-3-(1,3-二噻烷-2-基)丙烷。t.)下与正丁基锂在四氢呋喃中发生锂化反应;生成的阴离子与 2,3-二取代环氧乙烷、反式-2-甲基-3-(三苯甲氧基甲基)环氧乙烷(22)在 r.t、得到令人满意的偶联产物。另一方面,(S)-2-(1,3-二噻烷-2-基)-1-(4-甲氧基苄氧基)丙烷与正叔丁基锂在乙醚中形成的锂盐在六甲基磷酸三酰胺存在下与 22 在r.t.发生反应,得到偶联产物,产率中等。此外,还发现一种混合有机金属试剂 n-BuLi / Bu2Mg 是 9 的有效金属化试剂,由此产生的阴离子与 22 反应得到偶联产物,收率很高。