SolutionsAddition of N-acyliminium ions
Exercise 1
Why is an N-acyliminium ion more electrophilic than an iminium ion with alkyl substituents on the nitrogen?
The acyl group is electron-withdrawing: the nitrogen lone pair is partly delocalized towards the carbonyl, and the nitrogen stabilizes the positive charge of the C=N+ double bond less well. The iminium carbon therefore has more carbocation character and reacts even with weak nucleophiles such as allylsilanes or silyl enol ethers.