Diastereo- and Enantioselective Synthesis of<i>syn</i>- and<i>anti</i>-1,2-Diol Units by Asymmetric Aldol Reactions
作者:Teruaki Mukaiyama、Isamu Shiina、Hiromi Uchiro、Shu Kobayashi
DOI:10.1246/bcsj.67.1708
日期:1994.6
syn- and anti-1,2-Diol units were prepared by using asymmetric aldol reactions of the silyl enol ethers derived from α-alkoxythioacetic S-esters with aldehydes. In the presence of tin(II) triflate, a chiral diamine, and dibutyltin diacetate, (Z)-2-benzyloxy-1-ethylthino-1-(trimethylsiloxy)ethene reacted with aldehydes to afford the corresponding anti-aldol adducts in high yields with excellent diastereo- and enantioselectivities, while syn-adducts were obtained from (Z)-2-(t-butyldimethylsiloxy)-1-ethylthio-1-(trimethylsiloxy)ethene and aldehydes under the same reaction conditions. Thus, both diastereomers can be synthesized in excellent enantiomeric excesses by simply choosing the protective groups of the alkoxyl parts of the silyl enol ethers.
通过利用α-烷氧基硫代乙酸S-酯与醛的不对称缩醛反应,制备了反式和顺式1,2-二醇单元。在存在三氟甲磺酸锡(II)、手性二胺和二丁基二乙酸锡的情况下,(Z)-2-苄氧基-1-乙硫基-1-(三甲基硅氧基)乙烯与醛反应,以高收率生成具有优异非对映性和对映选择性相应的反式缩醛加合物,而顺式加合物则是在相同的反应条件下由(Z)-2-(叔丁基二甲基硅氧基)-1-乙硫基-1-(三甲基硅氧基)乙烯和醛生成的。因此,通过简单地选择硅醇醚烷氧基部分的保护基团,即可以优异的对映选择性合成两种非对映体。