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

Abstract

The first discrete seven-membered cyclic zinc(II) complex catalyzed room temperature Knoevenagel condensation reactions, and the synthesis of perimidine derivatives has been reported under mild reaction conditions. The cyclic zinc(II) complex [(L)ZnBr 2 ] (1) was isolated from the reaction between 1-(2-hydroxyethyl)-3-isopropyl-benzimidazol-2-thione (L) and ZnBr 2 . Complex 1 was characterized by different analytic techniques such as FT-IR, CHNS, TGA, NMR, and SCXRD. The mononuclear zinc(II) complex 1 was utilized as a catalyst for Knoevenagel condensation reactions to isolate twenty different substituted methylene malononitriles with excellent yield. Besides, the zinc(II) thione complex 1 was utilized for the synthesis of 2,4-dihydroperimidine derivatives in a highly efficient manner. Catalyst 1 depicted wide substrate scopes. Overall, twenty different substituted methylene malononitriles and nine different perimidine derivatives were synthesized using catalyst 1 at room temperature. The present investigation features a mild and fast synthetic approach along with excellent functional group tolerance.

Mechanochemical synthesis of Zn-bionanohybrids: size effect at the nanoscale to improve their enzyme-like activity

“…[11][12] In particular, the synthesis of Zn catalysts has attracted great interest due to its high abundance in the earth's crust (0.0076%), its affordability, and its non-toxicity. 13 Surprisingly, the interest in zinc as a catalyst has been underdeveloped, but recently this situation is changing 14 and the potential of zinc has been demonstrated in several applications such as C-C, C-N and C-O bond formation reactions, [15][16][17] and in solid surface reactions such as acylation of alcohols, phenols and amines. [18][19] Therefore, the development of methods for the synthesis of highly active, selective, stable and robust zinc nanoparticles (ZnNPs) is of great interest.…”