posted on 2019-05-28, 00:00authored byGuo-Hui Yang, Qun Zhao, Zhi-Pei Zhang, Han-Liang Zheng, Li Chen, Xin Li
A BINOL-based chiral phosphoric acid
was employed as an efficient
catalyst in enantioselective cycloaddition of ortho-hydroxyphenyl-substituted para-quinone methides
and enamides, which gave rise to acetamido-substituted tetrahydroxanthenes
with three adjacent stereogenic centers in high yields (up to 99%)
and excellent stereoselectivities (up to >99:1 diastereomeric ratio
and up to 98% ee).