Trading N and O: asymmetric syntheses of β-hydroxy-α-amino acids via α-hydroxy-β-amino esters
作者:Stephen G. Davies、Ai M. Fletcher、Aileen B. Frost、James A. Lee、Paul M. Roberts、James E. Thomson
DOI:10.1016/j.tet.2013.08.007
日期:2013.10
the C(2)-position via a sequential oxidation/diastereoselective reduction protocol gave the corresponding enantiopure 2,3-syn-α-hydroxy-β-amino esters in >99:1 dr. These syn- and anti-substrates were then converted into the corresponding N-Boc protected cis- and trans-aziridines, respectively, via a three step reaction sequence: (i) hydrogenolysis and in situ N-Boc protection; (ii) OH-activation; and
2-氨基-3-羟基丁酸和2-氨基-3-羟基-3-苯基丙酸的非对映体都已经从对映纯的α羟基-β氨基酯通过相应的中间性制备顺式和-反式-aziridines。2个α的氨羟化,β -不饱和酯制备对映纯的2,3-反-α羟基-β-氨基> 99酯:1个博士。在通过连续的氧化/还原非对映选择性的协议C(2) -位随后差向异构化,得到相应的对映体纯2,3-顺-α-羟基-β氨基酯在> 99:1个博士。这些顺式-和反然后-substrates被转化成相应的Ñ -Boc保护的顺式-和反式-aziridines,分别经由三步反应过程:(i)氢解和就地Ñ -Boc保护; (ii)OH活化;和(iii)氮丙啶的形成。随后的区域选择性的C(3) -甲基氮丙啶的有Cl开环3 CCO 2 ħ继续进行配置,以得到相应的2-氨基-3-三氯乙酸酯的反转,而与C(3)的类似反应-苯基-氮丙啶导致重排为相应的恶唑烷-2-酮与结构的保