Control of remote stereochemistry using phosphine oxides: formal synthesis of any stereoisomer diol (RR, RS, SR or SS ) bearing 1,5-related stereogenic centres across an E double bond
作者:Adam Nelson、Stuart Warren
DOI:10.1039/a903371h
日期:——
γ-Alkenyl β-hydroxy phosphine oxides have been epoxidised stereoselectively to give γ,δ-epoxy β-hydroxy phosphine oxides with high anti stereoselectivity. The γ-anisyl or γ-furyl ring of γ-aryl β-hydroxy phosphine oxides have been cleaved oxidatively to reveal a carboxylic acid and a ketone respectively. In the latter case, the ketone was reduced highly stereoselectively to give (4R*,5S*,6R*)-8-benzyloxy-6-diphenylphosphinoyloctane-1,4,5-triol as a single diastereoisomer with three controlled stereogenic centres. This method was then applied to the synthesis of three of the diastereoisomers of 8-benzyloxy-6-diphenylphosphinoyldodecane-1,4,5-triol with four controlled stereogenic centres; the middle two stereogenic centres were removed using an E-selective Horner–Wittig elimination to give either diastereoisomer of 8-benzyloxydodec-5-ene-1,4-diol with 1,5-related stereogenic centres across an E alkene.
γ-烯基β-羟基膦氧化物经过立体选择性环氧化反应,得到具有高抗立体选择性的γ,δ-环氧β-羟基膦氧化物。γ-芳基β-羟基膦氧化物的γ-茴香基或γ-呋喃基环被氧化裂解,分别得到一个羧酸和一个酮。在后一种情况下,酮被高度立体选择性还原,得到(4R*,5S*,6R*)-8-苄氧基-6-二苯基膦酰基辛烷-1,4,5-三醇,作为具有三个可控立体中心的单一非对映异构体。然后,这种方法被用于合成具有四个可控立体中心的8-苄氧基-6-二苯基膦酰基十二烷-1,4,5-三醇的三个非对映异构体;中间的两个立体中心通过E选择性霍纳-维蒂格消除反应被去除,得到具有1,5-相关立体中心的8-苄氧基十二碳-5-烯-1,4-二醇的两个非对映异构体,它们通过E烯烃相连。