. A solution of 2-trimethylsiloxybieyclo[5.3.03dec-l-ene (56 mg, 0.25 mmol) in 3 ml of 1,2-dimethoxyethane with a few milligrams of triphenylmethane as an indicator was treated with methyllithium at 25°until a color persisted. Then methyl iodide (0.3 ml) was added and the mixture stirred for 2 min. Water was added and the product extracted with 2 X 50 ml portions of hexane. An oil, 29 mg (71 %), was obtained upon evaporation of 1-methylbicyclo-[5.3.0]decan-2-one (48). The oil was a single spot by tic on silica gel: ir (CC14) 1736, 1412, 1374 cm"1; nmr (CC14) 1.13 (s) and 1.17 (s) total 3 H, cis and trans isomers; 1.2-2.3 (mult, 15 H); ms m/e (%) 166 (0.4), 151 ( 16), 110 (100), 95 (75), 81 (77), 68 (42), 67 (56), 55 (43), 41 (67). Anal. Caled for CuHlaO: 166.13576. Found: 166.13321. Acknowledgment. We thank the National Science Foundation and the National Institutes of Health for their generous support of our programs. We also thank the National Science Foundation and the Wisconsin Alumni Research Foundation for support in the purchase of nmr and mass spectrometric facilities.

The condensation of diphenylsulfonium cyclopropylide with aldehydes and ketones generates oxaspiropentanes in 59-100% yields. Whereas dialkyl and arylalkyl ketones allow easy isolation of these reactive compounds, the oxaspiropentanes from benzophenone and cyclopropyl methyl ketone are not isolable but rearrange to the cyclobutanones. 3-Methyloxaspiropentanes are equally accessible (83-100%) by use of diphenylsulfonium 2-methylcyclopropylide. With cyclohexanones equatorial attack occurs exclusively. Treatment of such intermediates with lithium diethylamide in hexane leads to 1 -viny 1-1 -cyclopropanols which may be directly derivatized with trimethylchlorosilane to give the silyl ethers. Base treatment of the viny Icy clopropanols generates 1-propionyl olefins, whereas acid treatment generates cyclobutanones. Thermal rearrangement produces the enolsilyl ethers of cyclopentanones which may be hydrolyzed with aqueous hydrochloric acid to the cyclopentanone or cleaved to the lithium enolate with methyllithium. The overall process is annelation of a cyclopentanone ring regiospecifically onto a carbonyl compound possessing an -methyl or methylene group. This cyclopentane annelation method proceeds in overall yields of 73-85%.Oxaspiropentanes, monooxygen analogs of spiropentanes, are highly strained molecules which

4.3 mmol) of 0.54 Af m-trifluoromethylphenylmagnesium bromide. Distillation of the crude product at 96-97°( 0,5 mm) yielded 1.05 g (84%) of 1 -/H-trifluoromethylphenylcyclohexanol: ir (CC14) v 3625 (OH), 3050 (ArH), 2950 and 2875 (aliphatic CH), 1325 (sym CF3Ar), 1170 (asym CF3Ar), 1130 (asym CF3Ar), 702 (aromatic); uv *'° 271 nm (e 7300), 263 (8700), 257 (7500), 252 sh (6400); nmr (CC14) 1.4-2.0 (11 H, m, -(CH2)4-and OH), 7.3-7.9 (4 H, m, ArH); mass spectrum m/e (70 eV) (rel intensity) 244.16381

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