2002 thiopyran derivatives

thiopyran derivativesR 0370

11 - 123Stereoselective Synthesis of Thiochroman-4-ones by Ring Transforma-tion of Chiral 5-Ylidene-1,3-dioxan-4-ones with 2-Bromothiophenolvia Bromo–Lithium Exchange. — A novel asymmetric synthesisof thiochromanones (V) and (VII) is presented, involving the reaction ofalkylidenedioxanones (I) and (VI), resp., with bromothiophenol (II) followed bynucleophilic attack of the aryl ring at the carbonyl carbon and subsequent ringtransformation. Depending on the configuration of the Michael adducts (III)or (IV), the hydroxyethyl group remains intact during ring transformation oris cleaved off. — (ALI, AKBAR; AHMAD, VIQAR UDDIN; LIEBSCHER,JUERGEN; Eur. J. Org. Chem. (2001) 3, 529-535; Inst. Chem., Humboldt-Univ., D-10115 Berlin, Germany; EN)

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