Highly Chemoselective Trichloroacetimidate-Mediated Alkylation of Ascomycin: A Convergent, Practical Synthesis of the Immunosuppressant L-733,725
作者:Zhiguo Song、Anthony DeMarco、Mangzhu Zhao、Edward G. Corley、Andrew S. Thompson、James McNamara、Yulan Li、Dale Rieger、Paul Sohar、David J. Mathre、David M. Tschaen、Robert A. Reamer、Martha F. Huntington、Guo-Jie Ho、Fuh-Rong Tsay、Khateeta Emerson、Richard Shuman、Edward J. J. Grabowski、Paul J. Reider
DOI:10.1021/jo981805g
日期:1999.3.1
L-733,725, a new immunosuppressant drug candidate, was prepared by a highly chemoselective alkylation of the macrolide ascomycin at the C32 hydroxy position with the imidazolyl trichloroacetimidate 16. The trichloroacetimidate-activated side chain 16 was prepared by an efficient four-step sequence in 42% overall yield. The high chemoselectivity in the alkylation of the C32 hydroxy group of the unprotected
L-733,725,一种新的免疫抑制剂药物,是通过大环内酯类抗霉素在C32羟基位置与咪唑基三氯乙酰亚氨酸酯16高度化学选择性烷基化制备的。三氯乙酰亚氨酸酯活化的侧链16通过高效的四步法在42中制备总产率%。未保护的子囊霉素的C32羟基在烷基化反应中的高化学选择性是供电子保护基团对咪唑16(极性适中的碱性溶剂)和强酸催化剂的协同作用的结果。发现N,N-二甲基新戊酰胺与乙腈混合是最好的溶剂,三氟甲磺酸是最好的催化剂。这种合成加上L-733的树脂柱纯化,