Premium
Synthesen von Dibenzo[ b , e ][1,4]dioxin‐2,3‐chinonen, einschliesslich der Ecklonochinone A und B sowie der Isoecklonochinone A und B
Author(s) -
Lütolf Walter Leo,
Prewo Roland,
Bieri Jost H.,
Rüedi Peter,
Eugster Conrad Hans
Publication year - 1985
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19850680407
Subject(s) - chemistry , yield (engineering) , quinone , toluene , medicinal chemistry , stereochemistry , organic chemistry , materials science , metallurgy
Syntheses of Dibenzo[ b , e ][1,4]dioxin‐2,3‐quinones Including the Ecklonoquinones A and B and the Isoecklonoquinones A and B Oxidation of monomesyloxy‐substituted pyrocatechols with MnO 2 in toluene using phase‐transfer conditions leads in high yield to monomesyloxy‐substituted dibenzo[ b , e ][1,4]dioxin‐2,3‐quinones with loss of one mesyloxy group. In this way, ecklonoquinone A ( 2 ), ecklonoquinone B ( 3 ), isoecklonoquinone A ( 43 ), and isoecklonoquinone B ( 44 ) were prepared. Their structures are based on X‐ray analyses of ecklonoquinone‐A leucoacetate ( 45 ) and the mesyloxy‐substituted quinone 20 . The reddish‐violet dibenzodioxin‐diquinone 49 was prepared from an intermediate of the iso‐series. The parent compound 1 has been synthesized in yields better than 50% from pyrocatechol and methyl 2,5‐dioxo‐2,5‐dihydrobenzoate as oxidant and 2‐methoxypyridin as catalyst. To rationalize the specific effect on the dimerisation step of the mesyloxy group, the intermediacy of 1,4‐quinone monoacetals is proposed. This also applies to a proposed biogenetic scheme.