ISSN:
0170-2041
Schlagwort(e):
Cyclopentane-1,3-diones, 2,2-disubstituted
;
Cyclopentane-1,3-dione, 2-methyl-
;
Cycloheptane-1,4-dione, (±)-5-methyl-
;
Bicyclo[3.2.1]octane-2,6,8-trione, (±)-5-methyl-
;
Chemistry
;
Organic Chemistry
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
Notizen:
In contrast to earlier reported unsuccessful experiments the Michael addition of prop-2-enal to 2-methylcyclopentane-1,3-dione (1) affords 3-(1-methyl-2,5-dioxocyclopentyl)propanal (3) in 90% yield, if the reaction is carried out in water without a basic catalyst. This aldehyde is converted by an intramolecular aldol reaction to (±)-endo-2- and (±)-exo-2-hydroxy-5-methylbicyclo[3.2.1]octane-6,8-dione (rac-4 and rac-6), both affording (±)-5-methylcycloheptane-1,4-dione (rac-8) after oxidation to (±)-5-methylbicyclo[3.2.1]octane-2,6,8-trione (rac-2), hydrolytic ring-opening and decarboxylation. This reaction sequence allows the transformation of the 2-alkylated cyclopentane-1,3-dione 1 into the 5-alkylated cycloheptane-1,4-dione rac-8 in a good overall yield. The pathway of the ringopening process has been determined by an investigation of the reaction intermediates.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/jlac.199219920176
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