5- and 6-Exocyclic Products, <i>cis</i>-2,3,5-Trisubstituted Tetrahydrofurans, and <i>cis</i>-2,3,6-Trisubstituted Tetrahydropyrans via Prins-Type Cyclization
作者:Satish. N. Chavre、Hyunah Choo、Jae Kyun Lee、Ae Nim Pae、Youseung Kim、Yong Seo Cho
DOI:10.1021/jo800967p
日期:2008.10.3
Exocyclic products having cis-2,5 and cis-2,6 substitution were synthesized from terminally substituted alkynyl alcohols with various aldehydes via Prins-type cyclization in good yields. It is of interest that synthesized 5- and 6-exocyclic vinyl cations generated as a result of Prins-type cyclization could be trapped as a vinyl triflate in CH2Cl2 to give 3-furanylidenes and 3-pyranylidenes. Those
通过末端取代的炔醇与各种醛基通过Prins型环化合成具有顺式-2,5和顺式-2,6取代的环外产物,收率很高。令人感兴趣的是,由于Prins型环化而生成的合成的5-和6-外环乙烯基阳离子可能会被捕获为三氟甲磺酸乙烯酯,而形成CH 2 Cl 2,从而生成3-呋喃基和3-吡喃基。将那些3-呋喃基亚烷基和3-吡喃基亚胺水解,得到具有全顺式构型的异构体的相应的3-酰基取代的产物,例如2,3,5-三取代的四氢呋喃和2,3,6-三取代的四氢吡喃。