Studies of Unusual Amino Acids and Their Peptides. VI. The Syntheses and the Optical Resolutions of β-Methylphenylalanine and Its Dipeptide Present in Bottromycin
bromide with acetaminomalonate, followed by the hydrolysis and decarboxylation of the condensate. The decarboxylation occurred diastereoselectively to some extent. The erythro and the threo isomers could be separated by the fractional crystallization of their benzoyl derivatives, and differentiated by means of their NMR spectra. The opticalresolution of the respective isomers was attained by treating
β-甲基苯丙氨酸是通过α-甲基溴化苄与乙酰氨基丙二酸酯缩合,然后将缩合物水解和脱羧来制备的。脱羧在一定程度上非对映选择性地发生。赤型和苏型异构体可以通过它们的苯甲酰基衍生物的分级结晶来分离,并通过它们的 NMR 光谱进行区分。各异构体的旋光拆分是通过用奎宁或奎尼丁处理苄氧羰基衍生物来实现的;因此,可以得到纯态的四种异构体。通过将 N-保护的赤型-L-β-甲基-苯丙氨酸与 L-β-(2-噻唑基)-β-丙氨酸酯或更方便地与 DL 偶联来合成存在于肉毒杆菌素 C 末端的二肽-复合,然后分离。
A method for determining absolute configuratiom of β-amino acids by CD spectra of their DNP derivatives