Cyclodienones. Part 8. Hydrolysis of 5-oxo-2,4-di-t-butylcyclopenta-1,3-dienecarbonitrile

Abstract

The acid-catalysed hydrolysis of 5-oxo-2,4-di-t-butylcyclopenta-1,3-dienecarbonitrile (2) gave the novel products 3,3a,6,6a-tetrahydro-3,3,3a-trimethyl-5-t-butyl-1H-cyclopenta[c]furan-1,6-dione (5), 4,5-dimethyl-7-t-butylbicyclo[3.3.0]octa-3,6-diene-2,8-dione (6), and 2-carbamoyl-5-isopropylidene-3-methylcyclopent-2-enone (7), but not the expected carboxylic acid (3). Treatment of compound (5) with 10% NaOH followed by acidification with 10% HCl gave, in 88% yield, the unexpected 2-methyl-5-oxo-4-t-butylcyclopent-1-enecarboxylic acid (8) which, on thermolysis, gave 3-methyl-5-t-butylcyclopent-2-enone (9) and 4-methyl-2-t-butylcyclopent-3-enone (10) in 51 and 36% yields, respectively.

The base catalysed hydrolysis of compound (2) has also been attempted.