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Aldol addition

4 real reactions from the literature, on methyl ketones, dialkyl ketones, β-keto esters and esters. Each scheme shows starting materials, conditions and products, with the yield and reference where the source reports them.

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  1. Aldol addition: acetone (a methyl ketone) with Ba(OH)2; Δ gives diacetone alcohol (the β-hydroxy ketone).
    Aldol additionOrg. Synth. Coll. Vol. 1, p. 199

  2. Aldol addition: a dialkyl ketone with 1) TiCl4 / Ti(OiPr)4, -78 C / CH2Cl2, 2 min; 2) iPr2NEt / 30 min; 3) 1.5 equiv 3-methylbutanal gives the β-hydroxy ketone.
    Aldol additionJ. Org. Chem. 2005, 70, 6533

  3. Aldol addition: a β-keto ester with 1) LDA, -78 C; 2) isobutyraldehyde gives the β-hydroxy ketone.
    Aldol additionJ. Am. Chem. Soc. 1988, 110, 3560

  4. Aldol addition: (2,4,6-trimethylphenyl) propanoate (an ester) and isobutyraldehyde (an aliphatic aldehyde) with 1) LDA, THF; 2) isobutyraldehyde gives 2,4,6-trimethylphenyl 3-hydroxy-2,4-dimethylpentanoate (the β-hydroxy ester). 60% yield.
    Aldol additionOrg. Synth. 1985, 63, 99