Synlett 2023; 34(09): 1019-1022 DOI: 10.1055/a-2024-4595
letter
Published as part of the Special Edition Thieme Chemistry Journals Awardees 2022
[3,3]-Rearrangements of N -Oxyindoles
Kashif Ali
,
Milan Bera
,
Eun Jin Cho∗
We are grateful for the support provided by a Chung-Ang University Young Scientist Scholarship for K. A. in 2022 and for support by the National Research Foundation of Korea (NRF-2020R1A2C2009636).
Abstract
The concerted Ag-catalyzed rearrangement of N -indolyl carbonates and esters to afford 3-oxyindole derivatives with broad functional-group compatibility is presented. In addition, this concerted [3,3]-rearrangement approach was expanded to the synthesis of phosphonate and sulfonamide derivatives without the use of an Ag catalyst. Control experiments suggested that no radical pathway is involved at any stage of the rearrangement process.
Key words
silver triflate -
oxyindoles -
rearrangement -
indolyl carbonates -
indolyl esters
Supporting Information
Supporting information for this article is available online at https://doi.org/10.1055/a-2024-4595.
Supporting Information
Publication History
Received: 22 November 2022
Accepted after revision: 01 February 2023
Accepted Manuscript online: 01 February 2023
Article published online: 23 February 2023
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Represented procedure : Synthesis of ethyl (2-phenyl-1H-indol-3-yl) carbonate (2a ); An oven-dried An oven-dried 10-mL resealable reaction tube equipped with a stirrer bar was charged with carbonate 1a (56 mg, 0.2 mmol) and AgOTf (10 mol%, 5 mg). The tube was then evacuated and refilled with argon twice. DCE (0.1 M, 2 mL) was added under an argon counterflow, and the mixture was stirred at 40 °C until the reaction was complete (TLC, ~12 h). The crude mixture was concentrated under reduced pressure and purified by flash column chromatography [silica gel, hexanes–EtOAc (4:1)] to give a yellowish liquid 2a , yield: 44 mg (79%). 1 H NMR (600 MHz, CDCl3 ): δ = 8.02 (br s, 1 H), 7.67 (dd, J = 8.4, 1.1 Hz, 2 H), 7.50 (dd, J = 7.9, 1.0 Hz, 1 H), 7.46 (dd, J = 8.4, 7.8 Hz, 2 H), 7.34 (tt, J = 7.8, 1.1 Hz, 1 H), 7.33 (dd, J = 8.0, 1.0 Hz, 1 H), 7.21 (ddd, J = 8.0, 7.2, 1.0 Hz, 1 H), 7.15 (ddd, J = 7.9, 7.2, 1.0 Hz, 1 H), 4.34 (q, J = 7.1 Hz, 2 H), 1.39 (t, J = 7.1 Hz, 3 H). 13 C NMR (151 MHz, CDCl3 ): δ = 153.8, 133.6, 130.6, 129.3, 128.1, 127.9, 126.4, 126.3, 123.4, 122.2, 120.8, 117.8, 111.6, 65.4, 14.5.