Chiral metal-organic frameworks bearing free carboxylic acids for organocatalyst encapsulation.
Two chiral carboxylic acid functionalized micro- and mesoporous metal-organic frameworks (MOFs) are constructed by the stepwise assembly of triple-stranded heptametallic helicates with six carboxylic acid groups. The mesoporous MOF with permanent porosity functions as a host for encapsulation of an enantiopure organic amine catalyst by combining carboxylic acids and chiral amines in situ through acid-base interactions. The organocatalyst-loaded framework is shown to be an efficient and recyclable heterogeneous catalyst for the asymmetric direct aldol reactions with significantly enhanced stereoselectivity in relative to the homogeneous organocatalyst.
School of Chemistry and Chemical Engineering and State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240 (China). liuy@sjtu.edu.cn.
Yan
Y
Liu
Xiaobing
X
Xi
Chengcheng
C
Ye
Tengfei
T
Gong
Zhiwei
Z
Yang
Yong
Y
Cui
aldol reactions; heterogeneous catalysis; metal-organic frameworks; organocatalysis; porous materials