Catalyst-Free One-Pot Access to Pyrazoles and Disulfide-Tethered Pyrazoles via Deamidative Heteroannulation of β-Ketodithioesters with Semicarbazide Hydrochloride in Water

Koley, S and Panja, SK and Soni, S and Singh, MS (2018) Catalyst-Free One-Pot Access to Pyrazoles and Disulfide-Tethered Pyrazoles via Deamidative Heteroannulation of β-Ketodithioesters with Semicarbazide Hydrochloride in Water. In: Advanced Synthesis and Catalysis, 360 (9). pp. 1780-1785.

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Abstract

An operationally simple, mild, and catalyst-free one-pot protocol to access privileged pyrazoles and disulfide-tethered pyrazoles has been devised by 3+2 heteroannulation of β-ketodithioesters with semicarbazide hydrochloride in water under open air. The pH of the medium played a key role toward the selectivity switch, as refluxing in water led to the formation of pyrazoles, whereas addition of sodium acetate in water enabled the formation of disulfide-tethered pyrazoles. Notably, this protocol involves a tandem sequence of amination/cyclization/dehydration/hydrodesufurization/hydrolysis/deamidative reactions. A mechanistic rationale for this regio-/chemoselective domino reaction is outlined, which is well supported and validated by density functional theory calculations. (Figure presented.). © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Item Type:	Journal Article
Publication:	Advanced Synthesis and Catalysis
Publisher:	Wiley-VCH Verlag
Additional Information:	The copyright for this article belongs to the Wiley-VCH Verlag.
Keywords:	deamidation in water; density functional theory calculation; disulfane; pH selective reaction; Pyrazole
Department/Centre:	Division of Chemical Sciences > Inorganic & Physical Chemistry
Date Deposited:	08 Aug 2022 05:30
Last Modified:	08 Aug 2022 05:30
URI:	https://eprints.iisc.ac.in/id/eprint/75561

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