Cyclopentanedione to 1,4-Cyclohexanedione Transformation

2-Dialkylated 1,3-cyclopentanediones undergo facile (3-dicarbonyl cleavage on treatment with aqueous alkali, and this process constitutes an excellent synthesis of 5-substituted 4-oxoalkanoic acids. The conversion of 1 into 2 was presumed to proceed in this way for more than 10 years. Closer examination of this transformation, however, revealed the situation to be more complex. When 1 was treated with one equivalent of sodium hydroxide in water at room temperature and the reaction was stopped after 2 minutes, 3 was obtained in ca. 50% yield. Treatment of 3 with excess sodium hydroxide solution gave a good yield of 2. 

Give mechanistic explanations for (a) the presumed pathway for conversion of 1 into 2, and (b) the unusual 1,3-cyclopentanedione - 1,4-cyclohexanedione transformation 1 3. 

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