We developed a novel asymmetric Friedel–Crafts alkylation/transamidation tandem reaction for the enantio- and diastereoselective synthesis of pyrazolo[3,4-b]pyridin-6-ones bearing a −CF₃ unit via synergistic chiral phosphoric acid and MgSO₄ catalysis. This [3 + 3] annulation protocol allows the formation of trifluoromethylated pyrazolo[3,4-b]pyridin-6-ones with two adjacent tertiary stereocenters in moderate to high yields (up to 90%), enantioselectivities (up to 97% ee), and diastereoselectivities (up to >20:1 dr).

中文翻译：

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手性磷酸和MgSO4协同催化不对称[3+3]环化构建三氟甲基吡唑并[3,4-b]吡啶-6-酮

我们开发了一种新颖的不对称 Friedel-Crafts 烷基化/转酰胺基串联反应，用于通过协同手性磷酸和 MgSO ₄催化合成带有 -CF ₃单元的吡唑并[3,4- b ]吡啶-6-酮的对映选择性和非对映选择性。这种 [3 + 3] 环化方案允许以中等至高产率（高达 90%）、对映选择性（高达 97% ee ) 和非对映选择性（高达 >20:1 dr）。