A convenient method for 3-pyrroline synthesis

[GRAPHICS] The synthesis of a range of 3-pyrrolines has been achieved from primary ami ne starting materials using a two-step alkylation/alkylldene carbene CH-Ins ertion reaction sequence. We have shown that insertion into a range of CH-b ond types is possible, and the formation of nitrogen-bearing quaternary ste reocenters is a relatively facile process. The insertion reaction occurs wi th > 95% retention of stereochemistry, but the presence of protecting group s on nitrogen is generally deleterious to the cyclization process.