Dinicotinic acid reacted with L-phenylalanine affording N-dinicotinoyl-bis-L-phenylalanine (VII). The same product was also obtained by mild alkaline hydrolysis of the corresponding ester VI. Coupling of VII with L-ornithine or L-ornithine methyl ester gave rise to the formation of the desired chiral bicyclic tripeptides IIIa and IIIb as enniatin analogues.
烟酸与L-苯丙氨酸反应生成N-烟酰基-双L-苯丙氨酸(VII)。相应酯VI经轻碱水解也得到相同产物。VII与L-鸟氨酸或L-鸟氨酸甲酯偶联,形成所需的手性双环三肽IIIa和IIIb,类似恩尼亚丁。