Azacrown core

Carbohydrate-derived azacrown ethers have been intensely studied as phase-transfer catalysts for the conjugate addition of 2-nitropropane to chalcones [172]. Various structural modifications have been introduced both in the azacrown core and in the carbohydrate (o-glucose, o-mannitol, and o-mannose) unit in order to obtain good enantioselectivities, the best results been obtained with o-glucose and D-mannose derivatives 113-117 (Scheme 2.60). 

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