A novel synthesis of precocenes. Efficient synthesis and regioselective O??alkylation of dihydroxy??2, 2??dimethyl??4??chromanones
T Timár, JC Jászberényi
Index: Timar, Tibor; Jaszberenyi, J. Csaba Journal of Heterocyclic Chemistry, 1988 , vol. 25, p. 871 - 877
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Citation Number: 31
Abstract
Abstract The reactions of trihydroxybenzenes 1a-c and 3-methylbut-2-enoic acid (2) in a zinc chloride/water/phosphoryl chloride system afford either the new trihydroxyphenylbutenone derivatives 3b, c or dihydroxy-2, 2-dimethyl-4-chromanones 4a-c in good yields. Compounds 3b, c can be cyclized in high yields to 4b, c in 5% sodium hydroxide solution. Regioselective O-alkylation of 4a-c leads to 5a-f in good yields. O-Alkylation of 5a-f, ...
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