Enantioselective Diels−Alder Reactions of Optically Active (Buta-1,3-dien-2-yl)(salen)cobalt(III) Complexes

Broadly Effective Enantioselective Diels−Alder Reactions of 1-Amino-substituted-1,3-butadienes

“…We had previously reported 5 that 1-amino-3-siloxybutadienes undergo DA reactions with a wide range of α-substituted acroleins catalyzed by Jacobsen's chiral Cr(III)-salen catalyst, − to give cycloadducts in excellent yield (>90%) and up to 97% ee. The primary cycloadducts are readily hydrolyzed, providing quick entry into synthetically useful 4-substituted or 4,5-disubstituted cyclohexenones. , Upon further consideration of the early results and the model put forth to explain the observed enantioselectivity, we hypothesized that although the enol ether moiety may enhance the reactivity of the diene (by raising the HOMO energy), it is unlikely to play a role in the enantiodifferentiation (Figure ).…”

The bigger, the better: Ring-size effects of macrocyclic oligomeric Co(iii)-salen catalysts

“…While the force field bonded and van der Waals parameters were used for the center of the Co-salen complex as described above, the equilibrium bond lengths and bond angles were taken from a structure of the complex determined by X-ray diffraction. Although a number of Co(III)-salen X-ray diffraction structures have been published in recent years, [38][39][40] there are no available X-ray diffraction data on a structure using the acetate counterion. The aforementioned bond length and bond angle parameters were taken from the structure reported by Cohen and coworkers on Co(III)-salen which utilizes a chlorine counter-ion.…”

Actinide Selective Systems for Environmental Extraction and Sensing Applications

“…Several asymmetric 2-quinoxalinol salens compounds (5) have been obtained based on the identified 2-quinoxalinol imines (3). Several asymmetric 2-quinoxalinol salens compounds (5) have been obtained based on the identified 2-quinoxalinol imines (3).…”

“…1 Salen-based ligands have been most widely used as supports for stereoselective catalysis in asymmetric epoxidation, 2 Hetero-Diels-Alder reactions, 3 hydrocyanation, 4 and other reactions. For example, copper (I) salen complexes have been investigated as an antitumor agents and found to be more bioactive than the antitumor drug cisplatin.…”