ANNULATED BICYCLO[2.2.2]OCTENONES - 9-HYDROXY-9-CHLOROMETHYL-ENDO-TRICYCLO )]UNDECA-4,10-DIENE-3-SPIRO(1'-CYCLOPROPANE)-8-ONE AND -ENDO-TRICYCLO[8.2.2.0(2,9)]TETRADECA-13-EN-11-ONE

A single crystal X-ray diffraction study of two annulated bicyclo[2.2. 2]octenones has been carried out to establish their precise stereostru ctures. The compounds, with their crystal data, are: 1, ]undeca-4,10-d iene-3-spiro(1'-cyclopropane)-8-one, C14H15O2Cl, space group P2(1)/c, a = 10.540(2), b = 9.668(1), c = 11.841(4)Angstrom, beta = 95.67(2)deg rees, Z = 4, and 3 -chloromethyl-endotricyclo[8.2.2.0(2,9)]tetradeca- -13-en-11-one, C15H21O2Cl, space group C2/c, a = 20.747(8), b = 6.498( 1), c = 20.525(3)Angstrom, beta = 93.04(3)degrees, Z = 8. The molecule of 1 has endo stereochemistry at the ring junction and the spirocyclo propane ring is proximal to the hydroxyl group. In 2, the eight member ed ring deviates from a chair conformation and one ring atom is disord ered. Crystals of 1 and 2 contain centrosymmetric dimers formed by C=O ... O-H hydrogen bonds.