Synthesis of five-, six-, seven-, eight-, and nine-membered cyclic α-hydrazino acids from a common starting material ‘diethylmalonate’ with 26, 16, 34, 13.5, and 13.33% overall yields is described. Sequential allylation or homoallylation and electrophilic amination followed by cyclization gave the desired rings. The methyl esters of eight- and nine-memberedrings were synthesized by RCM and the corresponding
描述了从常见的起始原料“丙二酸二乙酯”以26、16、34、13.5和13.33%的总收率合成五元,六元,七元,八元和九元环状α-肼基酸。顺序烯丙基化或均烯丙基化和亲电胺化,然后环化,得到所需的环。通过RCM合成八元环和九元环的甲酯,并在DCM中的1 M BBr 3溶液存在下水解后生成相应的游离酸。
Improved Synthesis of Cyclic <font>α</font>-Hydrazino Acids of Five- to Nine-Membered Rings and Optical Resolution of 5,6,7-Membered Ring Hydrazino Acids
to the diastereomers either via the formation of peptides with L-phenylalanine methyl ester or via the formation of esters (for five- to seven-memberedrings) with L-2-phenylalaninol. All diastereomers were separated except the nine-membered ring by flash chromatography. Hydrolysis of diastereomeric esters generated the optically pure five-, six- and seven-membered cyclic α-hydrazino acids. In this process