J. Am. Chem. SOC.1990, 112, 1011-7019 ~ m e r .This ~ transformation can also be accomplished quantitatively by chromatography of Sc,d on Florisil at -50 O C . I o The mechanism of the Florisil-promoted closure is unclear, but its stereochemistry is identical with that observed in the thermal closure. Assignment of the endo-D configuration to 7b is supported by spectroscopy and chemical reactivity studies. s4-Cyclopentadiene complexes of Rh(1) containing exo-H atoms have been shown to exhibit an anomalously low C-H stretching frequency (
