Highly efficient and recoverable dendritic organocatalyst from click chemistry for the asymmetric michael addition of ketones to nitroolefins without the use of organic solvent

A series of pyrrolidine-triazole based dendritic catalysts have been synthesized and applied directly in the asymmetric Michael addition of ketones to nitroolefins without the use of an organic solvent. Good yields (up to 99%), and high diastereoselectivities (up to syn/anti = 45:1) and enantioselectivities (up to 95% ee) have been obtained. Furthermore, the third generation catalyst can be reused at least five times without significant loss of catalytic activity.

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(S)-4-(4-((3,5-Bis(benzyloxy)benzyloxy)methyl)phenyl)-1-(pyrrolidin-2-ylmethyl)-1H-1,2,3-triazoleC35H36N4O3[α]D20=+9.1 (c 1.0, CH2Cl2)Absolute configuration: (S)Source of chirality: l-proline

(S)-4-(4-((3,5-Bis(3,5-bis(benzyloxy)benzyloxy)benzyloxy)methyl)phenyl)-1-(pyrrolidin-2-ylmethyl)-1H-1,2,3-triazoleC63H60N4O7[α]D20=+4.5 (c 1.0, CH2Cl2)Absolute configuration: (S)Source of chirality: l-proline

(S)-4-(4-((3-(3,5-Bis(3,5-bis(benzyloxy)benzyloxy)benzyloxy)-5-(3-(2,4-bis(benzyloxy)benzyloxy)-5-(3,5-bis(benzyloxy)benzyloxy)benzyloxy)benzyloxy)methyl)phenyl)-1-(pyrrolidin-2-ylmethyl)-1H-1,2,3-triazoleC119H108N4O15[α]D20=+2.8 (c 1.0, CH2Cl2)Absolute configuration: (S)Source of chirality: l-proline