Frequency of C-allylations on oligoglycinates via N-ylides.

The highly selective mono-C-allylation of oligoglycinates such as a diethylenetriaminepentaacetate, an iminodiacetate, and an ethylenediaminetetraacetate via insertion of a vacuum operation between the N-allylation and C-migration steps is reported. It is contrastive that one-pot N-allylation-C-allylation procedure gave a mixture including multiallylated products. In the reaction with N-ylides, gem-C-diallylation and α,α'-C-diallylation of oligoglycinates are strongly inhibited even with the use of an excess of allyl bromide and base. A mechanism to explain this control of the frequency of C-allylation on oligoglycinates via N-ylides is also proposed.