Synthesis 2023; 55(10): 1543-1552
DOI: 10.1055/a-2017-6065
paper

Transition-Metal-Free Dehydrogenative Cyclization via α-Csp3–H Activation of Ethers and Thioethers

Kartic Manna
a   Organic and Medicinal Chemistry Division, CSIR-Indian Institute of Chemical Biology, 4 Raja S. C. Mullick Road, Jadavpur, Kolkata-700032, West Bengal, India
b   Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, Uttar Pradesh, India
,
Hasina Mamataj Begam
a   Organic and Medicinal Chemistry Division, CSIR-Indian Institute of Chemical Biology, 4 Raja S. C. Mullick Road, Jadavpur, Kolkata-700032, West Bengal, India
,
Ranjan Jana
a   Organic and Medicinal Chemistry Division, CSIR-Indian Institute of Chemical Biology, 4 Raja S. C. Mullick Road, Jadavpur, Kolkata-700032, West Bengal, India
b   Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, Uttar Pradesh, India
› Institutsangaben
This research was funded by the Science and Engineering Research Board (SERB, DST, India; Core Research Grant No. CRG/2021/006717). KM and HMB thank the Council of Scientific and Industrial Research, India (CSIR) for their fellowships.


Abstract

We report herein the tetraethylammonium bromide catalyzed intramolecular oxidative cyclization of O- or S-alkylated salicylic or thiosalicylic acid derivatives to access 4H-benzo[d][1,3]dioxin-4-ones or 4H-benzo[d][1,3]oxathiin-4-ones, respectively. The oxidative cyclization of salicylic acid derivatives proceeds through a radical pathway at 110 °C. In contrast, the cyclization of the thiosalicylic acids proceeds smoothly at room temperature via an ionic pathway. Notably, the overall reactions are fast, completed within short reaction times, furnishing the products in high yields and with smooth formation of quaternary carbon centers.

Supporting Information



Publikationsverlauf

Eingereicht: 02. November 2022

Angenommen nach Revision: 23. Januar 2023

Accepted Manuscript online:
23. Januar 2023

Artikel online veröffentlicht:
27. Februar 2023

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