98795-02-9

Upstream product

• 24623-65-2 3-tert-butyl-2-hydroxybenzaldehyde 
• 32044-22-7 (1R,2R)-1,2-diaminocyclohexane tartrate 
• 88-18-6 2-tert-Butylphenol 
• 116407-32-0 (1R,2R)-(-)-1,2-diammoniumcyclohexane mono-L-(+)-tartrate 

Relevant academic research and scientific papers

Ring-opening polymerization of lactide using chiral salen aluminum complexes as initiators: High productivity and stereoselectivity

A family of aluminum complexes bearing chiral salen ligands derived from (R,R)-1,2-diammoniumcyclohexane mono-(+)-tartrate salt and modified by salicylaldehyde were prepared. The complexes were characterized by 1H, 13C NMR and elemen

Mechanistic basis for high stereoselectivity and broad substrate scope in the (salen)Co(III)-catalyzed hydrolytic kinetic resolution

In the (salen)Co(III)-catalyzed hydrolytic kinetic resolution (HKR) of terminal epoxides, the rate- and stereoselectivity-determining epoxide ring-opening step occurs by a cooperative bimetallic mechanism with one Co(III) complex acting as a Lewis acid and another serving to deliver the hydroxide nucleophile. In this paper, we analyze the basis for the extraordinarily high stereoselectivity and broad substrate scope observed in the HKR. We demonstrate that the stereochemistry of each of the two (salen)Co(III) complexes in the rate-determining transition structure is important for productive catalysis: a measurable rate of hydrolysis occurs only if the absolute stereochemistry of each of these (salen)Co(III) complexes is the same. Experimental and computational studies provide strong evidence that stereochemical communication in the HKR is mediated by the stepped conformation of the salen ligand, and not the shape of the chiral diamine backbone of the ligand. A detailed computational analysis reveals that the epoxide binds the Lewis acidic Co(III) complex in a well-defined geometry imposed by stereoelectronic rather than steric effects. This insight serves as the basis of a complete stereochemical and transition structure model that sheds light on the reasons for the broad substrate generality of the HKR.

(R,R)-salen/salan-based polymer fluorescence sensors for Zn2+ detection

(R,R)-salen-based polymer fluorescence sensor P-1 could be synthesized by the polymerization of 5,5′-(isoquinoline-5,8-diylbis(ethyne-2,1-diyl))- bis(3-tert-butyl-2-hydroxybenzaldehyde) (M-1) with (R,R)-1,2-diaminocyclohexane (M-2) via nucleophilic addition-elimination reaction, and (R,R)-salan-based polymer sensor P-2 could be obtained by the reduction reaction of P-1 with NaBH4. The fluorescence response behaviors of two chiral polymers P-1 and P-2 on Zn2+ were investigated by fluorescence spectra. The fluorescence intensities of P-1 and P-2 can exhibit gradual enhancement upon addition of Zn2+. Compared with other cations, such as Na +, K+, Mg2+, Ca2+, Fe3+, Co2+, Ni2+, Cu2+, Ag+, Cd 2+, Cr3+ and Pb2+, Zn2+ can lead to the pronounced fluorescence enhancement as high as 22.8-fold for P-1 and 3.75-fold for P-2, respectively. The results show that P-1 and P-2 incorporating (R,R)-salen/salan moieties as receptors in the polymer main chain backbone can exhibit high sensitivity and selectivity for Zn2+ detection.

Chiral linear polymers bonded alternatively with salen and 1,4-dialkoxybenzene: Synthesis and application for Ti-catalyzed asymmetric TMSCN addition to aldehydes

The synthesis of chiral linear polymers 1a-b having salen and 1,4-dioctyloxybenzene as alternate segments has been accomplished. The GPC analysis showed the molecular weights corresponding to ca. 15 (Mw = 10,999, Mn = 9165 and PDI = 1.20) repeating units for 1a and ca. 8 (Mw = 8547, Mn = 7883 and PDI = 1.08) repeating units for 1b. Polymers 1a-b have been studied with Ti(OiPr)4 as a recyclable catalyst for the asymmetric addition of TMSCN to aldehydes while the selectivity of the polymer catalyst is identical to that of the monomer. The reactions are efficient affording the cyanohydrins with up to 88% ee. The selectivity of the polymer based catalyst 9a is found to be the same to that of the monomer 10a. The reaction provides the advantages of simplified product isolation and easy recovery and recyclability of polymer catalyst 9a without any loss of activity or selectivity.

Polycarbonates made using highly selective catalysts

Poly(propylene carbonates) are prepared from propylene oxide and CO2 with less than 10% cyclic propylene carbonate by product using cobalt based catalysts of structure preferably in combination with salt cocatalyst, very preferably cocatalyst w