Pseudo-macrocyclic chelation control in remote asymmetric induction. Highly efficient 1,7-asymmetric inductive hydride reduction and Grignard reaction of gamma-keto esters of 1,1 '-binaphthalen-2-ols bearing an appropriate oligoether group as the 2 '-substituent

Highly efficient 1,7-asymmetric induction was achieved in DIBAL-H reduction and Grignard reaction of gamma-keto esters of podand-type 1,1'-binaphthale n-2-ol derivatives bearing an appropriate oligoether group as the 2'-substi tuent. Thus, the DIBAL-H reduction of keto esters 4 in dichloromethane-tolu ene at -78 degrees 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 bu tan-4-olides 10-13 with up to 99% optical yield. The complexation experimen ts of keto ester 4b suggested that the highly efficient 1,7-asymmetric indu ction originated from the formation of a pseudo-macrocyclic magnesium compl ex composed of the podand keto ester and MgBr2.