8-HYDROXY-SUBSTITUTED ISOCOUMARINS BY LITHIATION OF BENZENE-DERIVATIVES PROMOTED BY BETA-FUNCTIONALIZED ALKYL-GROUPS - A REGIOSELECTIVE ANDSIMPLE SYNTHESIS OF OOSPOLACTONE
A. Ramacciotti et al., 8-HYDROXY-SUBSTITUTED ISOCOUMARINS BY LITHIATION OF BENZENE-DERIVATIVES PROMOTED BY BETA-FUNCTIONALIZED ALKYL-GROUPS - A REGIOSELECTIVE ANDSIMPLE SYNTHESIS OF OOSPOLACTONE, Gazzetta chimica italiana, 125(3), 1995, pp. 111-113
3-(3-hydroxyphenyl)-2-butanone (obtained in 3 steps from 3-bromophenol
and 3-chloro-2-butanone) was ketalised with ethylene glycol and prote
cted at the phenolic OH as the methoxymethyl ether. The intermediate d
iacetal thus obtained underwent hydrogen-metal exchange with n-butylli
thium; the metallated intermediate, after carbonation, methanolysis of
acetal groups and elimination of methanol, regioselectively afforded
the title compound (8-hydroxy-3,4-dimethylisocoumarin).