Deprotection of an Nα-Fmoc-protected glycocysteine derivative 7 with an excess of morpholine unexpectedly led to the fluorenylmethyl-protected thioether 8 in high yield. The suggested mechanism for this reaction comprises the addition of the cysteine thiolate on the exocyclic double bond of dibenzofulvene, which is formed during Fmoc deprotection. The influence of base concentration on this transprotection reaction was studied.
使用过量
吗啡啶对一个被Nα-Fmoc保护的甘
氨酸衍
生物7进行去保护反应,意外地高产率地生成了
芴甲基保护的
硫醚8。该反应的机理包括半胱
氨酸
硫醇负离子在Fmoc去保护过程中形成的
二苯基富烯上的外环双键上的加成。研究了碱浓度对这种转保护反应的影响。