A Set of phenyl sulfonate metal coordination complexes triggered Biginelli reaction for the high efficient synthesis of 3,4‐dihydropyrimidin‐2(1<i>H</i>)‐ones under solvent‐free conditions
Yong‐Tao Wang, Gui‐Mei Tang, Yu‐Song Wu
Abstract
Three new metal coordination complexes, namely, [Co ( DPE )(H 2 O) 4 ]( DPE )( BS ) 2 ( 1 ), [Co ( DPE ) 2 (H 2 O) 4 ]( ABS ) 2 ( 2 ), [Co ( DPE )(H 2 O) 4 ]( MBS ) 2 (CH 3 OH) 2 ( 3 ) [ DPE = ( E )‐1,2‐di (pyridin‐4‐yl) ethene, BS = phenyl sulfonic acid, ABS = p ‐aminobenzene sulfonic acid, MBS = p ‐methylbenzene sulfonic acid] were obtained under hydrothermal conditions. Complexes 1 ‐ 3 were structurally characterized by X‐ray single‐crystal diffraction, powder X‐ray diffraction and IR. Complexes 1 and 3 exhibit a one‐dimensional chain structure, and complex 2 does a zero‐dimensional one. These three complexes further generate a three‐dimensional supramolecular architecture via strong hydrogen bonding interactions and packing interactions. These three metal coordination complexes show high catalytic performance for green synthesis of a variety of 3,4‐dihydropyrimidin‐2(1 H )‐ones through the Biginelli reactions, which show several advantages such as excellent yields, short reaction times, eco‐friendly synthesis conditions, and simple isolated workup procedure. Interestingly, the order of catalytic activities for these catalysts is the following: 3 > 1 > 2 , which can be ascribed to the acidities and hydrophobic interactions of phenyl sulfonate groups.