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Crosslinked chiral polysiloxanes containing cinchona alkaloid derivatives were synthesized from poly (methylhydrosiloxane) by hydrosilylation reaction. The C3vinyl group of cinchona alkaloid derivatives were easily hydrosilylated with SiÀ H functional groups of poly(methylhydrosiloxane) by using Pt catalyst. The reaction between cinchona alkaloid dimers and poly(methylhydrosiloxane) and afforded the crosslinked chiral polysiloxanes. Partial hydrolysis of SiÀ H bonds with Pt catalyst during reaction resulted in a formation of extra crosslinkages of chiral polysiloxanes. Mixed solvent (toluene and DMF) system was employed for a successful immobilization of C6'À OH free cinchona alkaloid derivatives into poly(methylhydrosiloxane). Both cinchona alkaloid C9-ester and C9-urethane derivatives were incorporated into poly(methylhydrosiloxane) through SiÀ C bond. The resulted crosslinked chiral polysiloxanes were insoluble in common organic solvents. Their catalytic performance was evaluated in asymmetric Michael addition reactions. The chiral polysiloxanes of cinchona alkaloid having C6'À OH showed higher enantioselectivities (up to 99% ee) with sufficient catalytic activities in the Michael addition reactions. The chiral polysiloxanes were easily recovered by filtration or centrifugation method and could be reused for several times without losing their catalytic performance.[a] B. T. Kumpuga, Prof. S. Itsuno

Mizoroki–Heck (MH) polymerization of cinchonidine‐based sulfonamide dimers produces polymers containing a chiral sulfonamide moiety in each repeat unit. Quinidine sulfonamides are known to have excellent catalytic activity in the asymmetric Michael addition reaction of β‐ketoester and nitrostyrene. We found that cinchonidine sulfonamides used as bifunctional chiral catalysts showed even higher stereoselectivity in the same reaction. The polymers synthesized by MH polymerization also showed high levels of diastereo‐ and enantioselectivity (up to 99% enantiomeric excess) in the reaction. Owing to the insolubility of the polymeric catalysts, they were separated easily from the reaction mixture and reused several times without any loss of catalytic activity.