TY - JOUR T1 - Supramolecular catalysis with extended aggregates and gels: inversion of stereoselectivity caused by self-assembly. AU - Rodríguez-Llansola,Francisco, AU - Miravet,Juan F, AU - Escuder,Beatriu, PY - 2010/6/12/entrez PY - 2010/6/12/pubmed PY - 2010/12/14/medline SP - 8480 EP - 6 JF - Chemistry (Weinheim an der Bergstrasse, Germany) JO - Chemistry VL - 16 IS - 28 N2 - L-Proline-L-valine dipeptide derivatives, which self-assemble in toluene, have been studied as stereoselective catalysts in the conjugate addition of cyclohexanone to trans-beta-nitrostyrene. Remarkable effects on the stereoselectivity are observed associated to the aggregation of the catalyst. Outstanding differences were observed between the catalytic activity of compound 1, which forms supramolecular gels in toluene, and compound 2, which is not a gelator. In the former case, the enantioselectivity of the reaction was almost insensitive to changes in catalyst concentration and temperature, but in the case of compound 2, the catalytic activity was very much affected by those variables. Structural studies indicate that the results can be rationalized by taking into account significant conformational changes experienced by the catalytic L-proline derivatives associated with the aggregation process. The results highlight that catalyst self-assembly is a very important issue to consider in the stereoselective outcome of organocatalytic reactions. Especially relevant is the fact that the use of supramolecular gels as organocatalysts emerges as a technique that affords reliable and constant stereoselectivity in different conditions with the added value of easy catalyst recovery. SN - 1521-3765 UR - https://www.unboundmedicine.com/medline/citation/20540050/Supramolecular_catalysis_with_extended_aggregates_and_gels:_inversion_of_stereoselectivity_caused_by_self_assembly_ L2 - https://doi.org/10.1002/chem.201000654 DB - PRIME DP - Unbound Medicine ER -