Chromium (ll) Reductions With two minor exceptions (3d and 3e), treatment of the ocacetylenic ketones listed in Table 2 with chromium (ll) sulfate in aqueous dimethylformamide led to the respective transcnones (Scheme C and Table 3). Yields ranged from 40* 85%. If great care was taken to exclude oxygen from the reaction mixture, the reduction could be accomplished with as few as 2.5 equivalents of chromium (II); for ...