This CC, unlike Dy(OTf) 3, could catalyze the reaction with secondary and primary amines. Recently, we reported that compound 2CH 3CN ( 1Dy) exhibits similar catalytic efficiency, with only 1% loading. (45, 46) In this specific topology, five out of six, and six out of seven or eight, coordination sites are occupied by H 2L1 for the 3d and the Dy III centers, respectively ( Scheme S1, right). The Schiff base H 2L1 (44) ( Scheme S1 in the Supporting Information), along with 3d and 4f ions affords tetranuclear M II 2Ln III 2 (M = Co or Ni) CCs possessing a defect dicubane topology with two divalent 3d ions (center) and two trivalent 4f ions (wings) ( Scheme S1, middle). We have recently developed a new generation of 3d/4f CCs and have explored their catalytic behavior. (43) However, in both cases, the reaction works only for secondary amines. This reaction proceeds in high yields with the use of acidic ionic liquids under solvent-free conditions (42) or with the use of N-sulfonylimine, with p-toluenesulfonamide acting as a leaving group. However, Sc(OTf) 3 gave higher yields with primary anilines (R 2 = H see Scheme 1) than Dy(OTf) 3. (41) In this study, Dy(OTf) 3 and Sc(OTf) 3 were found to be the best catalysts, with 10% loadings. (40) Batey and Li used a variety of Lewis acids for the synthesis of trans-4,5-diaminocyclopentanones ( Scheme 1) from the domino condensation/ring-opening/electrocyclization reaction of furfuraldehyde with amines. (37-39) The interest in bifunctionalized cyclopentenones arises from the fact that they are versatile building blocks in the synthesis of natural products such as (+)-Nakadomarin A. The Nazarov cyclization exemplifies such an electrocyclization, providing access to important and useful cyclopentones, and Lewis acids catalyze this cyclization. ![]() Electrocyclizations are one of the most valuable transformations for the construction of carbon–carbon bonds.
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