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Mass spectra were obtained on an A.E.I. MS902 mass spectrometer using a direct insertion probe; source temperatures were maintained at 30-40 °C to minimize pyrolytic reactions. All samples were subjected to preparative gas chromatography prior to mass spectral analysis. All gas chromatography was performed on a Hewlett Packard 5750 instrument containing a 10 ft X 0.125 in. column packed with 10% UCW-98 on 80-100 Chromosorb S. The NMR spectra were obtained using deuter-iochloroform solvents on a Varían Model A-60 spectrometer. The chemical shift values are expressed in values (parts per million) relative to a tetramethylsilane internal standard. All column and thin-layer chromatography were performed on silica gel, using benzene as eluent, unless otherwise indicated. (27) G.