A convenient method has been developed to convert N a -H tetracyclicketone 1a into the two corresponding oxindoles[C(7)] diastereospecifically. Treatment of the N a -H, N b -benzyl tetracyclicketone 1a with t-BuOCl provided diastereomer 2a (related to Voacanga oxindoles), whereas the same process with N b -H (1b) or N b -benzoyl (1c) substituted analogs funished the diastereomers 2b and 2c (related to alstonisine), respectively.