Enantioselective 6-endo-trig Wacker-type cyclization of 2-geranylphenols: application to a facile synthesis of (−)-cordiachromene
作者:Kazuhiro Takenaka、Yugo Tanigaki、Mahesh L. Patil、C.V. Laxman Rao、Shinobu Takizawa、Takeyuki Suzuki、Hiroaki Sasai
DOI:10.1016/j.tetasy.2010.04.060
日期:2010.4
An enantioselective intramolecular oxidative cyclization of 2-geranylphenols catalyzed by a Pd(II)-spiro bis(isoxazoline) complex is reported. The reaction proceeds in a 6-endo-trig manner to give chromene derivatives in reasonable yields and with moderate enantioselectivities. This transformation can be applied to a protecting-group-free total synthesis of naturally occurring cordiachromene.
报道了Pd(II)-螺双(异恶唑啉)配合物催化的2-香叶基酚的对映选择性分子内氧化环化。反应以6-内-触发方式进行,以合理的收率和适度的对映选择性得到色烯衍生物。该转化可以应用于天然存在的堇青色烯的无保护基的全合成。