An efficient chiral squaramide-catalysed enantioselective Michael addition of pyrazolin-5-ones to 3-nitro-2H-chromenes afforded chiral heterocycles containing both chroman and pyrazolone derivatives in high to excellent yields (up to 98%) with high enantioselectivities (up to 96%) under very low catalyst loading (0.2 mol%).
一个高效的手性方酰胺催化的选择性马克尔加成反应,将吡唑啉-5-酮加到3-硝基-2H-色醇中,得到含有色醇和吡唑酮衍生物的手性杂环化合物,收率高达98%,对映选择性高达96%,在非常低的催化剂负载下(0.2 mol%)。