Mechanistic Study of Base-Promoted Rearrangement of 1,5-Dibromopentacyclo[5.3.0.02,5.03,9.04,8]decane-6,10-dione to 10-Oxa-9-oxopentacyclo[5.3.0.02,4.03,6.05,8]decane-3-carboxylic Acid

Abstract

The conversion of 1,5-dibromopentacyclo[5.3.0.02,5.03,9.04,8]decane-6,10-dione (1) to 10-oxa-9-oxopentacyclo [5.3.0.02,4.03,6.05,8]decane-3-carboxylic acid (6) on treatment with 5% aqueous potassium hydroxide was shown to proceed through 1, exo-7-dibromo-9-oxotetracyclo[4.3.0.02,5.03,8]nonane-endo-4-carboxylic acid (2). Treatment of 1 with the base in heavy water gave rise to 2-d-6 deuterated at the 2-position, but 2 gave the protium analog 6 after the same treatment. These results are discussed in relation to reactions of similar compounds which have been previously described in the literature.