Tandem in situ Generation of Azomethine Ylides and Base Sensitive Nitroethylene Dipolarophiles

We have studied the behaviour of 2-acetoxy-nitroethane derivatives in the presence of triethylamine and of an azomethine ylide generated also by the action of this base in the same reaction mixture. Under these conditions the nitro-olefins are generated and react in situ with the corresponding dipoles, giving pyrrolidine derivatives in moderate to good yields.