94244-79-8Relevant articles and documents
A Novel Synthesis of Precocenes. Efficient Synthesis and Regioselective O-Alkylation of Dihydroxy-2,2-dimethyl-4-chromanones
Timar, Tibor,Jaszberenyi, J. Csaba
, p. 871 - 877 (2007/10/02)
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 5percent sodium hydroxide solution.Regioselective O-alkylation of 4a-c leads to 5a-f in good yields.O-Alkylation of 5a-f, followed by reduction and dehydration, results in the formation of precocene 3 (7d) and its regioisomer 7a-c,e,f.Methylation of 4a-c gives 6g-i.Subsequent reduction and dehydration affords precocene 2 (7h) and its regiosiomers 7g,i.