N-(9-Fluorenylmethoxycarbonyl)aspartic acid β-tert-butyl ester (3b) [Fmoc-Asp(OBu-t)] and N-(9-fluorenylmethoxycarbonyl)-glutamic acid γ-tert -butyl ester (4b) [Fmoc-Glu(OBu-t)] were prepared from aspartic and glutamic acids by treatment with isobutene and 4-toluenesulfonic acid followed by Fmocsuccinimide in a novel two-step, one-pot procedure to give the title compounds in moderate yield. The major byproduct of the reaction is the corresponding α-tert-butyl ester, which can be easily separated and purified.
N-(9-
芴甲氧基羰基)
天冬氨酸β-叔丁酯(3b) [Fmoc-Asp(OBu-t)] 和N-(9-
芴甲氧基羰基)-谷
氨酸γ-叔丁酯(4b) [Fmoc -Glu(OBu-t)]由
天冬氨酸和谷
氨酸通过用
异丁烯和4-甲
苯磺酸处理然后用Fmoc琥珀
酰亚胺以新颖的两步一锅法处理来制备,以中等收率得到标题化合物。反应的主要副产物是相应的α-叔丁酯,它很容易分离和纯化。