New Observations Concerning the Stereoselectivity of Monoiodocarbene Additions: Contrary to our earlier claim, CHI gives endolexo isomer mixtures with cyclooctene. However, only endo-iodo compounds 7,8,10- 12 are obtained from COD and COT. Tricyclic compound 7 rearranges partially to bicyclic 9. X-ray structure determinations of 7 and 9 were performed.