Programmed Multiple C-H Bond Functionalization of the Privileged 4-hydroxyquinoline Template.
Chemistry 2021;
27:7764-7772. [PMID:
33848033 DOI:
10.1002/chem.202100929]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2021] [Indexed: 11/12/2022]
Abstract
The introduction of substituents on bare heterocyclic scaffolds can selectively be achieved by directed C-H functionalization. However, such methods have only occasionally been used, in an iterative manner, to decorate various positions of a medicinal scaffold to build chemical libraries. We herein report the multiple, site selective, metal-catalyzed C-H functionalization of a "programmed" 4-hydroxyquinoline. This medicinally privileged template indeed possesses multiple reactive sites for diversity-oriented functionalization, of which four were targeted. The C-2 and C-8 decorations were directed by an N-oxide, before taking benefit of an O-carbamoyl protection at C-4 to perform a Fries rearrangement and install a carboxamide at C-3. This also released the carbonyl group of 4-quinolones, the ultimate directing group to functionalize position 5. Our study highlights the power of multiple C-H functionalization to generate diversity in a biologically relevant library, after showing its strong antimalarial potential.
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