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Paper | Regular issue | Vol 55, No. 11, 2001, pp.2059-2074
Published online, 1st January, 1970
DOI: 10.3987/COM-01-9301
■ Stereoselective Syntheses of (E)- and (Z)-2,3-Dihydro-3-(1,2,4-triazolyl)-4H-1-benzopyran-4-one Oxime Ethers

Saeed Emami and Abbas Shafiee*

*Department of Chemistry, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran

Abstract

A synthesis of (E)- and (Z)-2,3-dihydro-3-(1H-1,2,4-triazol-1-yl)-4H-1-benzopyran-4-one oxime ethers [(E)- and (Z)-13] and (Z)-2,3-dihydro-3-(4H-1,2,4-triazol-4-yl)-4H-1-benzopyran-4-one oxime ethers [(Z)-17] are described. Ring closure of 2-(1,2,4-triazolyl)-2¢-hydroxyacetophenones (5 or 6) followed by reaction with HONH2.HCl gave the corresponding (Z)-oximes [(Z)-11 or (Z)-16]. O-Alkylation of (Z)-oximes afforded (Z)-oxime ethers [(Z)-13 or (Z)-17]. Reaction of (Z)-3-bromo-2,3-dihydro-4H-1-benzopyran-4-one oxime (18) with 1,2,4-triazole afforded (E)-oxime [(E)-11]. O-Alkylation of (E)-oxime gave the desired (E)-oxime ethers [(E)-13]. In addition, (Z)-oxime ethers [(Z)-13 or (Z)-17)] could also be obtained from the reaction of 2,3-dihydro-3-(1,2,4-triazolyl)-4H-1-benzopyran-4-ones (2 or 14) with O-(arylmethyl)hydroxylamine hydrochloride (19).