Chiral oxime ethers in asymmetric synthesis. O-(1-Phenylbutyl)benzyloxyacetaldoxime, a versatile reagent for the asymmetric synthesis of protected 1,2-aminoalcohols, α-amino acid derivatives, and 2-hydroxymethyl nitrogen heterocycles including iminosugars
作者:Tracey S. Cooper、Alexander S. Larigo、Pierre Laurent、Christopher J. Moody、Andrew K. Takle
DOI:10.1039/b500390c
日期:——
Addition of a range of organolithium and Grignard reagents to (E)-O-(1-phenylbutyl)benzyloxyacetaldoxime 1 in the presence of boron trifluoride diethyl etherate is highly diastereoselective. The resulting hydroxylamines undergo N-O bond cleavage upon treatment with zinc-acetic acid or molybdenum hexacarbonyl to give, after N-protection, protected 1,2-aminoalcohols 3 in high enantiomeric purity. Debenzylation
在三氟化硼二乙基醚化物的存在下向(E)-O-(1-苯基丁基)苄氧基乙醛肟1中添加一系列有机锂和格氏试剂是高度非对映选择性的。在用锌-乙酸或六羰基钼处理后,所得羟胺经历NO键裂解,以在N-保护后得到高对映体纯度的被保护的1,2-氨基醇3。3a和3d的脱苄基作用分别得到N-Boc(R)-丙氨醇和(S)-苯丙氨醇。羟胺2还用作α-氨基酸前体,2i被转化为N-甲酰基-(R)-丙氨酰基-(S)-(4-溴)苯丙氨酸酯7,即天然二肽的N-末端二肽。1,2-氨基醇衍生物的多功能性可以通过将其转化为5-,通过闭环易位反应,高对映体过量的6-和7-元2-羟甲基氮杂环15-19。二氢吡咯15的进一步反应得到亚氨基糖1,4-二脱氧-1,4-亚氨基-D-核糖醇。