Me‐BIPAM for the Synthesis of Optically Active 3‐Aryl‐3‐hydroxy‐2‐oxindoles by Ruthenium‐catalyzed Addition of Arylboronic Acids to Isatins |
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| Authors: | Prof?Dr Yasunori Yamamoto Masaaki Yohda Tomohiko Shirai Prof?Dr Hajime Ito Prof?Dr Norio Miyaura |
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| Institution: | 1. Frontier Chemistry Center, Faculty of Engineering, Hokkaido University, Kita 13, Nishi 8, Kita‐ku, Sapporo, 060‐8628 (Japan), Fax: (+81)?11‐706‐6560;2. Division of Chemical Process Engineering, Faculty of Engineering, Hokkaido University, Kita 13, Nishi 8, Kita‐ku, Sapporo, 060‐8628 (Japan) |
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| Abstract: | A chiral O‐linked C2‐symmetric bidentate phosphoramidite (Me‐BIPAM) was found to be efficient for the ruthenium‐catalyzed addition of arylboronic acids to isatins. Asymmetric synthesis of 3‐aryl‐3‐hydroxy‐2‐oxindoles by 1,2‐addition of arylboronic acids to isatins was carried out in the presence of RuCl2(PPh3)3]/(R,R)‐Me‐BIPAM and KF, resulting in an enantioselectivity as high as 90 % ee. It was found that the reaction with N‐protected isatins proceeds with high yields and good enantioselectivities. The best protective groups on the nitrogen atom were different depending on the substituents on the aromatic ring. The use of a N‐benzyl group resulted in excellent enantioselectivities in many substrates compared with other groups. |
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| Keywords: | 1 2‐addition 3‐substituted‐3‐hydroxy‐2‐oxindole boron isatin ruthenium |
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