Woldegiorgis AG, Han Z, Lin X. Asymmetric [3 + 3] Annulation to Construct Trifluoromethylated Pyrazolo[3,4-
b]pyridin-6-ones via Chiral Phosphoric Acid and MgSO
4 Synergistic Catalysis.
Org Lett 2022;
24:4058-4063. [PMID:
35613707 DOI:
10.1021/acs.orglett.2c01513]
[Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
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).
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