Toward an Artificial Aldolase

Abstract

A new functional polymer where proline is bonded to polystyrene through a 1,2,3-triazole linker depicts characteristics targeted for an artificial aldolase. In spite of the hydrophobicity of the polymer backbone, the resin swells in water with building of an aqueous microenvironment. This property, arising from the formation of a hydrogen-bond network connecting the proline and 1,2,3-triazole fragments, is translated into a very high catalytic activity and enantioselectivity toward direct aldol reactions in water.

Towards Continuous Flow, Highly Enantioselective Allylic Amination: Ligand Design, Optimization and Supporting

“…R. M. is grateful to the Spanish Ministerio de Ciencia e Innovación for a predoctoral fellowship. We also thank Dr. G. Gonzµlez and Dr. K. Gómez (ICIQ support unit) for their help with HRMAS 13 C NMR measurements and Dr. C. Rodríguez-Escrich for his assistance in the design and performance of the continuous flow system.…”

“…[11g] Taking into account the limitations associated to ligand anchoring through nucleophilic substitution, we have thoroughly investigated a new strategy for supporting catalysts onto Merrifieldtype resins through copper(I)-catalyzed Huisgen 1,3-dipolar cycloaddition (click chemistry) [12][13][14] and have shown that the resulting resins behave as highly active, enantioselective and diastereoselective, yet reusable, catalysts.…”

“…[11f, 13] On the other hand, we have recently described a new family of PHOX ligands derived from modular, enantiopure b-amino alcohols ( Figure 1). The presence of an additional alkoxymethyl substituent at C-5 in the oxazoline ring of 2a-d leads to improved catalytic characteristics with respect to analogous PHOX ligands also bearing a phenyl substituent in C-4, but lacking the alkoxymethyl substituent at C-5.…”

“…Elemental analysis of the final resins in conjunction with high-resolution magic angle spinning (HRMAS) 13 C NMR spectroscopy allowed us to establish that the oxazoline anchors to the resin in quantitative yield. Treatment of resins 7e,f with potassium diphenylphosphide in THF at 0 8C provided the desired click-PHOX resins 8e,f.…”

Diastereo‐ and Enantioselective Direct Aldol Reactions in Aqueous Medium: A New Highly Efficient Proline‐Sugar Chimeric Catalyst

“…In other words, in the transition state the organic non-polar reactants would be buried in the hydrophobic environment [18] whereas the entire system would be kept in water by a hydrophilic surface. After accomplishment of the reaction, the moderately polar aldol molecules would be squeezed out of the hydrophobic environment and locate themselves closer to the polar surface of the catalyst.…”