23074-20-6Relevant articles and documents
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 as the 2′-substituent
Tamai, Yasufumi,Hattori, Tetsutaro,Date, Masamitsu,Koike, Shinji,Kamikubo, Yoshinori,Akiyama, Masahiro,Seino, Kazuhiro,Takayama, Hideki,Oyama, Tomohito,Miyano, Sotaro
, p. 1685 - 1694 (1999)
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.
