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
作者:Yasufumi Tamai、Tetsutaro Hattori、Masamitsu Date、Shinji Koike、Yoshinori Kamikubo、Masahiro Akiyama、Kazuhiro Seino、Hideki Takayama、Tomohito Oyama、Sotaro Miyano
DOI:10.1039/a901775e
日期:——
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
在带有适当的寡醚基作为2'-取代基的podand型1,1'-联萘-2-醇衍生物的DIBAL-H还原和Grignard反应中实现了高效的1,7-不对称诱导。因此,在进一步还原生成的非对映体羟基酯1,4-二醇8之后,在–78°C下在过量的MgBr 2 ·OEt 2存在下,将二氯甲烷-甲苯中的酮酯4进行DIBAL-H还原。光学收率高达92%。酮的类似治疗酯4,5和7与格氏试剂,得到相应的4,4-二取代的丁基-4- olides 10-13光学收率高达99%。酮酸酯4b的络合实验表明,高效的1,7-不对称诱导作用是由由Podand酮酸酯和MgBr 2组成的假大环镁络合物的形成引起的。