Asymmetric organocatalysts chiral imidazoles

Nevertheless, photoactive MOFs also show unique photocatalytic properties that other materials cannot compete with, especially in organic synthesis applications. MOFs create the opportunity to combine photocatalyst with organocatalyst. One example is the chiral MOF, namely, Zn-PYIl, which exhibits high selectivity for photocatalytic asymmetric a-alkylation of aldehydes, as demonstrated in Fig. 4.13c. The Zn-PYll has also been synthesised via a PSM process of the parent MOF Zn-BClPl (top of Fig. 4.13c), which has been synthesised via solvothermal reaction from L-N-tert-butoxycarbonyl-2-(imidazole)-l-pyrrolidine (l-BCIP) [58]. The key point of the PSM process is the removal of the protective tert-butoxycarbonyl (Boc) moiety to expose active sites, which are likely to be the N — H of pyrrolidine of the L-BCIP molecules that is located within the channels according to dye adsorption test. This has been realised by microwave irradiation in dry lV,lV-dimethyl-formamide solution. The activated Zn-PYIl shows a high reaction efficiency (74 % in yield) and excellent enantioselectivity (92 % ee) in photocatalytic a-alkylation of aliphatic aldehydes compared to that of other MOFs. 

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