Chiral Tetraazacalix‐Triazine Derivatives as Organocatalysts for Asymmetric Direct Aldol Reactions: Synthesis and Enantioselective Evaluation

ABSTRACT

Novel tetraazacalix derivatives were synthesized and evaluated for their catalytic performance in direct asymmetric aldol reactions carried out in organic solvents. Chiral functionalities were introduced onto the tetraazacalix[2]arene[2]triazine and tetraazacalix[4]arene[2]triazine framework via reactions with ( S )‐(+)‐2‐Phenylglycinol. The resulting tetraazacalix derivatives exhibited high catalytic efficiency in the aldol reactions between ketone and various aldehydes. The experimental results demonstrated that the structural moiety of the catalyst plays a decisive role in controlling the stereochemical configuration of the aldol products. Under the optimized conditions, the aldol adducts were obtained in excellent yields of up to 92% and enantioselectivities reaching 95%.