Cobalt(II) chloride accelerated one-pot three-component synthesis of α-aminophosphonates at room temperature

Green, one-pot synthesis of α-aminophosphonates catalyzed by ZnI2 at room temperature

“…In previous reports, we have shown that catalysts such as boric acid [24] , sodium dihydrogen phosphate [25] and cobalt (II) chloride [26] catalyzed synthesis of α -aminophosphonates. However, there is a need to develop one-pot syntheses of α -aminophosphonates using new methods.…”

On the discovery and development of tandem 1,4- and 1,2-addition of phosphites to 1-azadienes

“…In fact, trialkyl phosphites have been used on several occasions to perform 1,2-additions on α,β-unsaturated imines and α-aminophosphonates can be isolated in the presence of dealkylating agents. 30,[40][41][42][43][44][45][46] Taking these facts in account, the initial steps of the tandem addition process are depicted in more detail in Scheme 11. Under the strongly acidic conditions, the imine is protonated in a near quantitative manner (k 2 >>k 1 ).…”

NiSO4·6H2O as a new, efficient, and reusable catalyst for the α-aminophosphonates synthesis under mild and eco-friendly conditions

“…The key step of this approach is the addition of the pentavalent phosphorus nucleophile to imine formed in situ between aldehyde and primary amine. Similar methods are described [38] using variety of catalysts, Lewis acids, and others such as; TiO 2 [13], SnCl 4 [21], ZnCl 2 [39], Sn(OTf) 2 [12], Cu(OTf) 2 Á7H 2 O [14], BiNO 3 Á5H 2 O [8], BF 3 -SiO 2 [28], ZrOCl 2 Á8H 2 O or ZrO(ClO 4 ) 2 Á6H 2 O [7], Cp 2 Zr(OSO 2 C 4 F 9 ) 2 Á2H 2 O [22], Cd(ClO 4 ) 2 ÁH 2 O [10], CoCl 2 Á6H 2 O [18], Sulfamicacid [27], TsCl [16], Fe/SWCNTs [31], FeCl 3 [29], etc. In spite of their advantages, these methods show some flaws.…”

“…In spite of their advantages, these methods show some flaws. Among their disadvantages, we quote the low afforded yield, tedious work-up procedures, the long reaction time [22], large amount of catalyst [18], heating or addition of some bases as activator factor [31], and an excessive use of organic solvents presenting a serious danger to the environment [29].…”