The present article aims to review the recent developments in asymmetric aldol reactions
under solvent-free conditions or in water. Asymmetric catalysis is undoubtedly the most popular technique
for realizing enantioselective synthesis of different target molecules. Prolines and Cinchona alkaloids
have emerged as very powerful chiral organocatalysts. There is continuous effort around the
globe to develop greener methodologies for organic syntheses. Researchers have made efforts to apply
the principles of green chemistry in asymmetric aldol reactions as well. The present review article
focuses on the recent development of enantioselective aldol reactions under solvent-free conditions or
in water as a green solvent. In many cases, such reactions occur at ambient temperature, thereby offering
energy-efficiency in those transformations. L-proline and its derivatives, especially amides, have
been observed to play prominent role in catalyzing asymmetric aldol reactions in aqueous medium or
under solvent-free conditions. The use of compounds derived from azetidine, L-serine, and morpholine
as catalysts in enantioselective aldol reactions in either aqueous medium or under solvent-less
condition is also described.
Keywords: Aldol, enantioselective, water, proline, solvent-free, β-hydroxycarbonyl compounds.
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