Enantioselective total synthesis of the di-O-methyl ethers of (–)-agatharesinol, (+)-hinokiresinol and (–)-sugiresinol, characteristic norlignans of Coniferae
作者:Osamu Muraoka、Bao-Zhong Zheng、Noriyuki Fujiwara、Genzoh Tanabe
DOI:10.1039/p19960000405
日期:——
enantioselective syntheses of the di-O-methyl ethers of the norlignans, (–)-agatharesinol (–)-1a, (+)-hinokiresinol (+)-2a and (–)-sugiresinol (–)-3a are described. Grignard addition of vinylmagnesium bromide to an aldimine (–)-13, prepared from the tert-butyl ester 11 and 4-methoxycinnamaldehyde 12, afforded a homochiral vinyl aldehyde, (–)-3-(4-methoxyphenyl)pent-4-enal (–)-14 in >95% ee, which was converted
描述了降冰片聚糖,(-)-agatharesinol(-)-1a,(+)-hinokiresinol(+)-2a和(-)-sugiresinol(-)-3a的二-O-甲基醚的简便对映选择性合成。在叔丁酯11和4-甲氧基肉桂醛12制备的醛亚胺(–)-13中,将乙烯基溴化镁进行格利雅(Grignard)加成,得到均手性乙烯基醛(-)-3-(4-甲氧基苯基)戊-4-烯醛(–)-14的ee大于95%,通过第二次Grignard反应,将其转化为1,3-双(4-甲氧基苯基)戊-4-烯-1-醇(3 R)-6的非对映异构体混合物4-甲氧基苯基溴化镁。乙烯醇(3 R)-6的Sharpless'不对称二羟基化非对映选择性进行,得到所需的相对立体化学三醇(2 S,3 S)-7。此,在脱水时,得到( - ) -二- Ö -methylsugiresinol( - ) - 3b中,其中随后的酸催化的环化反应,得到(