Reductive opening of 2,7-dihydrodinaphthoxepine and thiepine: easy regioselective preparation of 2,2′-difunctionalised binaphthyls
作者:Francisco Foubelo、Benjamín Moreno、Miguel Yus
DOI:10.1016/j.tetlet.2004.10.041
日期:2004.11
electrophiles [H2O, Me2CO, Et2CO, (CH2)4CO, (CH2)5CO], followed by hydrolysis with water, yields symmetrically 2,2′-disubstituted binaphthyls 7. In the case of starting from (R)-5a, the reductive opening by treatment with 2.2 equiv of lithium naphthalenide followed by reaction with H2O or (CH2)5CO as electrophiles and final hydrolysis, leads to enantiomerically pure compounds (R)-6aa and (R)-6af, respectively.
在-78°C下用2.2当量萘基锂在THF中的2,7-二氢二萘并杂庚烷(5)锂化生成双阴离子中间体8,该中间体通过与不同的亲电试剂[H 2 O,D 2 O,t BuCHO,Me 2 CO ,在同一温度下,Et 2 CO,(CH 2)4 CO,(CH 2)5 CO],然后水解,导致不对称的2,2'-双取代联萘6。当锂化是4,4'-二-催化量的存在下与过量的锂进行叔-丁基联苯(DTBB,10 mol%),进行两次还原裂解,得到双阴离子中间体9,该中间体通过与不同的亲电试剂[H 2 O,Me 2 CO,Et 2 CO,(CH 2)4 CO,(CH 2)5 CO],然后用水水解,对称地生成2,2'-di取代的双萘基7。在从(R)-5a开始的情况下,通过用2.2当量的萘二甲酸锂处理然后与H 2 O或(CH 2)5反应来进行还原性打开。CO作为亲电子试剂并最终水解,分别产生对映体纯的化合物(R)-6aa和(R)-6af。