Base-Promoted Rearrangement of Cage Aplha-Halo Ketones. 3. 3,6-Dibromotetracyclo(6.3.0.0(4,11).0(5,9)undecane-2,7-dione

摘要

Treatment of 3,6-dibromotetracyclo(6.3.0.0(4,11).0(5,9))undecane-2,7-dione (2) with solid sodium hydroxide in tetrahydrofuran at 25 C for 4 h afforded 7-bromopentacyclo-(5.4.0.0(2,6).0(3,10)0(5.9)undecane-8,11-dione (4). Treatment of 2 with solid sodium hydroxide in refluxing tetrahydrofuran for 4 h afforded instead pentacyclo-(5.3.0.0(2,6).0(3,10)0(4,8)decane-5-one-2-carboxylic acid (5). The intermediacy of 4 in the rearrangement of 2 to 5 was demonstrated. These rearrangements provide novel entries into the pentacyclo(5.4.0.0(2,6).0(3,10).0,9)undecyl and 1,3-bishomocubyl ring systems, respectively from a common tetracyclic precursor (i.e., 2). (Author)