Two new calix[4]resorcinarene-based coordination cages adjusted by metal ions for the Knoevenagel condensation reaction

Abstract

Two new calix[4]resorcinarene-based metal-coordinated cages have been synthesized through tuning metal ions, where they featured catalytic activities for the Knoevenagel condensation reaction under solvent-free conditions.

Highly Active Cyclic Zinc(II) Thione Catalyst for C−C and C−N Bond Formation Reactions

“…Based on the previous literature, [2–4,11–18] a plausible catalytic mechanism for the Knoevenagel condensation reaction is illustrated in scheme 7. We presume that zinc(II) in 1 can act as a Lewis acidic site to lead to catalytic activities.…”

“…The high yield synthesis of 2-phenyl-2,3-dihydro1-H perimidine derivatives catalyzed by 1 was accomplished using lower catalyst loading within 5 minutes under mild reaction conditions compared to known catalytic strategies, Cu(NO 3 ) 2 (5 mol%/RT/EtOH/10 min; Yield: 83%), [26] Nano-γ-Al 2 O 3 /SbCl 5 (solvent-free, RT, 95%), [24] Fe 3 O 4 /SO 3 H@zeolite-Y (EtOH, RT, 98%). [25] Based on the previous literature, [2][3][4][11][12][13][14][15][16][17][18] a plausible catalytic mechanism for the Knoevenagel condensation reaction is illustrated in scheme 7. We presume that zinc(II) in 1 can act as a Lewis acidic site to lead to catalytic activities.…”

“…The solid precipitate was dissolved in CH 3 OH to obtain colourless crystal of J H-H = 7.3 Hz, 1H, bimH), 7.31-7.18 (m, 2H, bimH), 5.55 (dt, 3 J H-H = 14.0, 7.0 Hz, 1H, N-CH), 4.92 (t, 3 J H-H = 5.6 Hz, 1H, OH), 4.35 (t, 3 J H-H = 5.7 Hz, 2H, N-CH 2 ), 3.77 (t, 3 J H-H = 5.6 Hz, 2H, CH 2 ), 1.53 (d, 3 J H-H = 7.1 Hz, 6H, 2CH 3 ). 13 C NMR (δ c ppm, DMSO-d 6 , 100.612 MHz): 167.6 (C=S), 132.9 (bimC), 129.5 (bimC), 122.3 (bimC), 110.6 (bimC), 110.4 (bimC), 58.4 (N-CH), 48.3 (N-CH 2 ), 47.0 (HO-CH 2 ), 19.5 (CH 3 ). FT-IR (neat, cm À 1 ) ῡ: 3093 (broad, OH), 2392 (w), 1569 (w), 1508 (w), 1415 (s), 1346 (w), 1261 (w), 1214 (w) 1168 (m), 952 (w), 798 (w), 740 (s), 694 (m), 647 (w).…”

“…Notably, the majority of these catalysts have been developed for the Knoevenagel condensation reactions. Zinc(II) clusters and metal‐organic frameworks have been used as the active catalysts for the Knoevenagel condensation reactions [11–17] . We presume that the unsaturated open metal sited of zinc(II) can act as Lewis acid sites while ligand can act as Lewis base sites to promote the catalytic application in Knoevenagel condensation reactions.…”

“…Zinc(II) clusters and metal-organic frameworks have been used as the active catalysts for the Knoevenagel condensation reactions. [11][12][13][14][15][16][17] We presume that the unsaturated open metal sited of zinc(II) can act as Lewis acid sites while ligand can act as Lewis base sites to promote the catalytic application in Knoevenagel condensation reactions. On account of earlier literature, the four coordinated zinc(II) complexes have been considered to be the coordinatively unsaturated open catalytically active metal sites.…”