Catalyst salicylaldimine-based

Strong interest in late transition metal olefin polymerization catalysts resulted in the development of new five-coordinate Fe and Co systems (69) that afford highly linear, crystalline, high-density polyethylene.587-589 A new class of single-component, neutral Ni catalysts based on salicylaldimine ligands (70) was reported to be active in the polymerization of ethylene 590,591... 

Grubbs group [31, 32] developed another type of Ni-based catalyst. This neutral Ni-catalyst, based on salicylaldimine ligands, is active in ethene polymerisation without any co-activator and originated from the Shell higher olefin process (SHOP). Shortly thereafter another active neutral P,0-chelated nickel catalysts for polymerisation of ethene in emulsion was developed by Soula et al. [33, 34, 35]. The historical development of single site catalysts is represented in Fig. 1. 

One of the most powerful catalysts of the Mukaiyama aldol reaction is a chiral Ti(IV)-Schiff base complex 91 prepared from Ti(0 Pr)4 and enantiomerically pure salicylaldimine reported by Carreira [103-105]. This catalyst furnished aldol adducts in good yields and with excellent enantioselectivity. The Ti(IV)-Schiff base catalyst system is unique among the aldol catalysts yet reported in terms of operational simplicity, catalyst efficiency, chirality transfer, and substrate generality. Because the Ti(IV)-Schiff base complexes are remarkably efficient catalysts for the addition of ketene acetals to a wide variety of aldehydes, the polymeric version of catalyst 92 was prepared [106]. The activity and enantioselectivity of the polymer-supported chiral Ti(IV)-Schiff base complex were, however, much lower than were obtained from the low-molecular-weight catalyst (Eq. 28). 

Higher yields of cyclic carbonates are obtained using chromium (iii) bis(salicylaldimine) complexes in combination with DMPA as a catalyst. Also, tetrahaloindate (m) based ionic liquids catalyze this reaction. From chloromethyloxirane and CO2 (7 bar) at 120 °C a 98 % yield of the corresponding carbonate is obtained . 

---