## 2 Results and Discussion
### The Effect of Solvent in an Asymmetric DA Reaction Catalyzed by ICCC 6  
The asymmetric DA reaction of (\(E\))-cinnamaldehyde **7** and 1,3-cyclopentadiene **8** catalyzed by ICCC **6** was carried out as a benchmark reaction (Scheme 3). The optimization of the reaction solvent was firstly investigated (Table 3). The reaction solvent in the asymmetric reaction using MacMillan catalyst significantly affected the catalytic reactivity, and did when using a homogeneous catalyst as well [40; 45; 56]. The reaction was performed with 10 mol % of catalyst **6** in a solvent at 25 \({}^{\circ}\)C for the comparison of the catalytic performance of **6** with those previously reported. The reaction time was determined by the consumption of **7** by TLC. Both the yield and enantiomeric excess (ee) were \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Entry** & **6** & **Solvent** & **Degree of Immobilization (\%)** & **Catalyst Content (mmol g-1)** \\ \hline
1 & **6d\({}_{\textbf{20}}\)C** & 1/1 THF/CH\({}_{3}\)OH & 61 & 0.533 \\
2 & **6d\({}_{\textbf{10}}\)B** & 1/1 THF/CH\({}_{3}\)OH & 67 & 0.581 \\
3 & **6d\({}_{\textbf{10}}\)B** & 1/1 CH\({}_{2}\)Cl\({}_{2}\)/CH\({}_{3}\)OH & 86 & 1.06 \\
4 & **6d\({}_{\textbf{10}}\)B-200** & 1/1 CH\({}_{2}\)Cl\({}_{2}\)/CH\({}_{3}\)OH & 98 & 1.10 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Characterization of ICCC **6**. Figure 2: SEM images. (**a**) **1d\({}_{\textbf{10}}\)B**, (**b**) **2d\({}_{\textbf{10}}\)B**, (**c**) **3d\({}_{\textbf{10}}\)B**, (**d**) **4d\({}_{\textbf{10}}\)B**, and (**e**) **6d\({}_{\textbf{10}}\)B**. increased by increasing the polarity of the reaction solvent (entries 1-4). The catalyst **6d10B** showed low reactivity with slightly low enantioselectivity (82% ee (_exo_)) when a highly polar solvent, such as H2O, was used as the solvent, which was probably due to poor dispersity of the polymer microsphere and the hydrophobic polymer chains (entry 4 versus 5). When dry MeOH was used, enantioselectivity was decreased (entry 4 versus 6), which indicated that a trace of H2O in the solvent assisted with increasing the ee value. There has been a report that the presence of H2O in the DA reaction catalyzed by the MacMillan catalyst enhances reactivity [56]. With the addition of H2O (in 95/5 THF/H2O or 95/5 CH3 CN/H2O), both reactivity and enantioselectivity were improved (entry 1 versus 7 and entry 3 versus 8). When a 95/5 MeOH/H2O mixed solvent was used, the catalyst showed excellent reactivity and enantioselectivity (92% ee (_exo_) >99% ee (_endo_)) (entry 9). When the amount of H2O in the mixed solvent was increased to 25 vol%, the yield and ee were decreased due to the decrease of dispersity of the catalyst (entry 11). From these results, 95/5 MeOH/H2O mixed solvent was accepted as the optimized reaction solvent for the asymmetric DA reaction. Comparison of the Catalytic Activity of a Model and Polymeric Macmillan Catalyst in an Asymmetric DA Reaction  
The catalytic activity of **6** was compared with that of the corresponding [PERSON] catalyst and another polymeric MacMillan catalyst in the same reaction (Table 4 and Figure 3). The original MacMillan catalyst **5 Cl** exhibited excellent reactivity with 93% ee (_exo_) and 93% ee (_endo_) (entry 1). The enantioselectivity of MacMillan catalyst with \(p\)-toluenesulfonate **5 OTs** was somewhat lower (entry 2). The linear-type polymeric catalyst in which MacMillan catalyst is immobilized at the pendant **10** (Figures S7-S9) exhibited high enantioselectivity comparable to the low molecular weight counterpart (entry 3). By contrast, the enantioselectivity of the gel-type polymeric catalyst **11** was decreased, possibly due to the steric hindrance or the conformational restriction by polymer network (entry 4). Even though the reactivity was somewhat low, the polymer microsphere-immobilized [PERSON] catalyst **12d20C** exhibited high enantioselectivity (entry 5). The ICCC **6d20C** exhibited