1.2.1.5 The Darzen Reaction

The base-catalyzed condensation between an a -halo ester and an aldehyde or ketone affords glycidic ester (Scheme 11).

Scheme 11

Examples:

1.2.1.6 The Knoevenagel Reaction

The condensation of methylene group bonded with two electron withdrawing groups with aldehydes or ketones using weak base is known as the Knoevenagel reaction (Scheme 12). The reaction is more useful with aromatic than with aliphatic aldehydes.

Scheme 12

Examples: