Diketopiperazinespirocyclopropane 12 is prepared in > 98% d.e. via the conjugate addition of a phosphorus ylide to (6S)-N,N′-bis(p-methoxybenzyl)-3-methylenepiperazine-2,5-dione 2. Deprotection and hydrolysis of adduct 12 and subsequent peptide coupling demonstrate the applicability of this methodology to the asymmetric synthesis of 1-aminocyclopropane-1-carboxylic acids for incorporation into novel peptides. A model for the high level of diastereofacial selectivity observed in the cyclopropanation reaction is presented. A highly selective asymmetric approach (> 98% d.e.) to (S)-[2,2-2H2]-1-aminocyclopropane-1-carboxylic acid 29 is also reported via a deuterated sulfur ylide addition to acceptor 2.
通过膦叶立德对(6S)-N,N'-双(对甲氧基苄基)-3-亚甲基
哌嗪-2,5-二酮2的共轭加成,制备了具有大于98%对映体纯度的二酮
哌嗪螺
环丙烷12。接着对加成物12进行脱保护和
水解,并进行肽键偶联反应,证明了此方法在不对称合成1-
氨基
环丙烷-1-
羧酸中的应用,可用于构建新型肽段。同时,我们还提出了在
环丙烷化反应中高程度非对映面选择性的模型。此外,通过
氘标记
硫叶立德对受体2的加成反应,报道了一种高度选择性的不对称合成途径(大于98%对映体纯度),用于制备(S)-[2,2-2H2]-1-
氨基
环丙烷-1-
羧酸29。