1-苯并硫代吡啶鎓盐2与共轭二烯的极性环加成反应在区域和立体上特异性地进行,从而以良好的产率得到相应的苯并稠合的双环sulf盐4。环加合物4与亲核试剂如甲醇或水的反应导致开环,分别得到2-(丁-2-烯基)-和2-(丁-3-烯基)-取代的2 H -1-苯并噻喃5和6。 。用多种碱处理环加合物4hA,得到螺环戊烯衍生物7和螺-1,2-二氧戊环衍生物8。讨论了涉及双自由基中间体的机理,用于基于化学方法形成上述产物7和8。证据。还描述了用硼氢化钠或氰基硼氢化钠还原环加合物4hA。
The first successful polar cycloaddition of 1-benzothiopyranylium salts with conjugated dienes and transformation of the cycloadducts
作者:Hiroshi Shimizu、Shojiro Miyazaki、Tadashi Kataoka、Mikio Hori
DOI:10.1039/c39920001586
日期:——
1-Benzothiopyranylium salts 1 underwent polar cycloaddition with conjugated dienes 2 to give benzo-fused bicyclic sulfonium salts 3 having sulfur at a bridgehead position in good yields, which were easily transformed into spiro compounds 4 and 5 by treatment with base.