A New Chiral P,N‐Ligand Derived from 1‐Phenylphospholane‐2‐carboxylic Acid (Phenyl‐P‐proline) for Palladium‐Catalyzed Asymmetric Allylic Substitution Reactions |
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Authors: | Xiang‐Min Sun,Masatoshi Koizumi,Kei Manabe,Shū Kobayashi |
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Abstract: | New types of P,N‐ligands, cis‐ and trans‐ 3 , containing a tetrahydroisoquinoline skeleton as an N‐donor were synthesized from (1R,2S)‐1‐phenylphospholane‐2‐carboxylic acid (phenyl‐P‐proline, 1 ). The cis isomer, cis‐ 3 , was found to act as an excellent ligand in palladium‐catalyzed asymmetric allylic substitution reactions. The reactions of 1,3‐diphenyl‐2‐propenyl acetate ( 5 ) with several nucleophiles in the presence of [Pd(π‐allyl)Cl]2, cis‐ 3 (Pd : ligand=1 : 2), and a base afforded the desired products in high yields with high enantioselectivity. It was suggested that these ligands did not serve as P,N‐bidentate ligands but as P‐monodentate ligands in these reactions. |
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Keywords: | allylic substitution asymmetric catalysis palladium P,N‐ligands |
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