Synthesis of 2-aminobenzofurans via base-mediated [3 + 2] annulation of N-phenoxy amides with gem-difluoroalkenes

Abstract

An efficient, mild and metal-free [3+2] annulation of N-phenoxy amides with gem-difluoroalkenes has been realized via base-mediated tandem [3,3]-sigmatropic rearrangement, which gives the direct access to 2-aminobenzofuran derivatives involving the...

Recent Advances in Alkenyl sp2 C–H and C–F Bond Functionalizations: Scope, Mechanism, and Applications

“…755 In a recent report, Zhou and Yi et al illustrated an effective and metal-free [3 + 2] annulation reaction of N-phenoxy amides with gem-difluoroalkenes through a Cs 2 CO 3 -promoted tandem [3,3]-sigmatropic rearrangement, providing a straightforward approach to assemble a variety of 2-aminobenzofurans in a one-pot reaction (Scheme 472). 756 757 A range of functional groups tolerated in this reaction to generate the expected products with excellent Z-stereoselectivity. Mechanistically, Ni(COD) 2 is first transformed into the active Ni(I)-L n complex I, which then undergoes borylation to form L n Ni(I)-Bpin species II.…”

“…illustrated an effective and metal-free [3 + 2] annulation reaction of N -phenoxy amides with gem -difluoroalkenes through a Cs 2 CO 3 -promoted tandem [3,3]-sigmatropic rearrangement, providing a straightforward approach to assemble a variety of 2-aminobenzofurans in a one-pot reaction (Scheme ). In this case, the reaction proceeded through the cleavage of multiple bonds involving C–H, O–N, and two C–F bonds. The utility of this strategy was hightlighted by the application of the on-DNA synthesis as well as the products’ applicability as potential anticancer agents.…”

“…755 In a recent report, Zhou and Yi et al illustrated an effective and metal-free [3 + 2] annulation reaction of N-phenoxy amides with gem-difluoroalkenes through a Cs 2 CO 3 -promoted tandem [3,3]-sigmatropic rearrangement, providing a straightforward approach to assemble a variety of 2-aminobenzofurans in a one-pot reaction (Scheme 472). 756 synthesis as well as the products' applicability as potential anticancer agents. 7.2.2.…”

Multiple-fold C–F bond functionalization for the synthesis of (hetero)cyclic compounds: fluorine as a detachable chemical handle

“…Beyond aryl gem-difluoroalkenes, styryl gem-difluoroalkenes displayed moderate reactivity, providing The next significant contribution to two-fold C(sp 2 )-F bond functionalization was made by Yi's group, which capitalized on a base-mediated tandem [3,3]-sigmatropic rearrangement/ [3 + 2] annulation cascade of N-phenoxy amides and gemdifluoroalkenes (Scheme 58). 105 Numerous 2-aminobenzofurans possessing potent antitumor activity were built on the basis of the mild reactions, which could be used for the preparation of pharmaceutical ingredients and natural products. For example, N-phenoxyacetamide derived from L-tyrosine underwent the defluorinative annulation smoothly to furnish 2-aminobenzofuran 58-3a in 58% yield.…”

A General Set of DNA-Compatible Reactions for Preparing DNA-Tagged Multisubstituted Pyrroles

“…Among them, the DNA-encoded libraries produced with drug-like chemical moieties enable improvement of the success rate of screening campaigns against biological targets. Consequently, considerable attention has been devoted to designing and synthesizing DNA-encoded libraries based on valuable heterocyclic central cores. − …”