Asymmetric aldol reactions catalyzed by new spiro diamine derivatives

Two new organocatalysts derived from l-proline and a novel chiral spiro diamine bearing a C2 symmetric backbone, were introduced for an asymmetric aldol reaction in moderate to good asymmetric induction in up to 76% ee and high yields.

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(S,S)-1,1′-Spirobiindane-7-amine-7′-(pyrrolidine-2-carboxylic acid amide)C22H25N3O[α]D25=-123.7 (c 0.27, CH2Cl2)Source of chirality: natural l-proline and resolutionAbsolute configuration: S,S

(S,S,S)-1,1′-Spirobiindane-7,7′-bis(pyrrolidine-2-carboxylic acid amide)C27H32N4O2[α]D25=-92.2 (c 0.27, CH2Cl2)Source of chirality: natural l-proline and resolutionAbsolute configuration: S,S,S