Rearrangement of Bridgehead Alcohols to Polycyclic Ketones by Fragmentation-Cyclization 4-Protoadamantanone

REARRANGEMENT OF BRIDGEHEAD ALCOHOLS TO POLYCYCLIC KETONES BY FRAGMENTATION-CYCLIZATION 4-PROTOADAMANTANONE 

Submitted by Zdenko Majerski and Zdenko Hamersak Checked by Thomas P Demuth and Andrew S Kende 

endo-7-Iodomethylbicyclo[3.3.1]nonan-3-one. A 2-1., threenecked, round-bottomed flask equipped with an efficient mechanical stirrer and a reflux condenser is charged with 600 ml. of dry benzene (Note 1). The flask is immersed in a water bath, stirring is initiated, and 58.3 g. (0.132 mole) of lead tetraacetate (Note 2), 37.4 g. (0.147 mole) of iodine, and 10.0 g. (0.066 mole) of 1-adamantanol (Note 3) are added (Note 4). The bath temperature is gradually raised to 80° over a 20-minute period and is then allowed to cool to 70-75°. Stirring is continued for 2 hours at 70-75° (Note 5) and for an additional hour while the mixture is cooled to room temperature The inorganic salts are filtered and tMrefully washed with five 50-ml. portions of ethyl ether. The 

Solvent-grade benzene was dried over sodium wire prior to use. If the benzene is wet, a considerable amount of starting 1-adamantanol remains unreacted owing to hydrolysis of lead tetraacetate. 

Lead tetraacetate, both purchased from Fluka AG, Buchs, 

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