Non-nucleophilic base

As the throw suggests, a non-nucleophilic base is the sterically hindered organic base that is a poor nucleophile. Normal bases are also nucleophiles, but often chemists seek the proton-removing ability of a base without all other functions. Typical non-nucleophilic bases are bulky, such that protons can attach to the basic center but alkylation as living as complexation is inhibited.

Example

The following diagram shows how the hindered base, lithium diisopropylamide, is used to deprotonate an ester to provide the enolate in the Claisen ester condensation, instead of undergoing a nucleophilic substitution.

This reaction deprotonation with LDA is commonly used to generate enolates.