Synthesis of Substituted α,β-Unsaturated Ketones, Pyrazoles, Isoxazoles and 2,4,6-Triarylpyrylium Chlorophosphates via β-Lithiation of Benzotriazolyl­vinyl Ethyl Ether

Abstract

Quenching the β-lithiated benzotriazolylvinyl ethyl ether 2 with aldehydes, acid chlorides and chalcones provided the corresponding β-hydroxyalkyl derivatives 4a-f, β-keto vinyl ethers 7a,b, and Michael adducts 8a,b, respectively. The alkylated product 4 was converted into α,β-unsaturated ketones 5a-f upon treatment with bromine. β-Keto vinyl ethers 7a,b cyclocondensed with hydrazines to afford pyrazoles 9a-d, and with hydroxylamine hydrochloride to give isoxazoles 10a,b. Treatment of 8 with phosphorus pentachloride resulted in the formation of 2,4,6-triarylpyrylium chlorophosphates 12.

Key words

heteroatom - β-lithiation - vinyl ethyl ether - benzotri­azole - electrophile

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