ChemInform Abstract: Pseudo-Macrocyclic Chelation Control in Remote Asymmetric Induction. Highly Efficient 1,7-Asymmetric Inductive Hydride Reduction and Grignard Reaction of γ-Keto Esters of 1,1′-Binaphthalen-2-ols Bearing an Appropriate Oligoether Group

Autor: Sotaro Miyano, Yoshinori Kamikubo, Tomohito Oyama, Yasufumi Tamai, Shinji Koike, Kazuhiro Seino, Hideki Takayama, Masamitsu Date, Tetsutaro Hattori, Masahiro Akiyama
Rok vydání: 2010
Předmět:
Zdroj: ChemInform. 30
ISSN: 1522-2667
0931-7597
DOI: 10.1002/chin.199944041
Popis: Highly efficient 1,7-asymmetric induction was achieved in DIBAL-H reduction and Grignard reaction of γ-keto esters of podand-type 1,1′-binaphthalen-2-ol derivatives bearing an appropriate oligoether group as the 2′-substituent. Thus, the DIBAL-H reduction of keto esters 4 in dichloromethane–toluene at –78 °C in the presence of an excess of MgBr2·OEt2 afforded, after further reduction of the resulting diastereomeric hydroxy esters, 1,4-diol 8 with up to 92% optical yield. A similar treatment of keto esters 4, 5 and 7 with Grignard reagents gave the corresponding 4,4-disubstituted butan-4-olides 10–13 with up to 99% optical yield. The complexation experiments of keto ester 4b suggested that the highly efficient 1,7-asymmetric induction originated from the formation of a pseudo-macrocyclic magnesium complex composed of the podand keto ester and MgBr2.
Databáze: OpenAIRE
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