作者:Johan J. N. Veerman、Robin S. Bon、Bui T. B. Hue、Daniel Girones、Floris P. J. T. Rutjes、Jan H. van Maarseveen、Henk Hiemstra
DOI:10.1021/jo0342572
日期:2003.5.1
with protic acid generated the corresponding N-acyliminium ion, which was trapped by a nucleophilic C2-side chain to provide 2,6-bridged piperazine-3-ones. Several aromatic, heteroaromatic, and nonaromatic side chains were used as pi-nucleophiles. In addition, the effect of the presence of a C5-methyl group on the stereochemical outcome of the cyclization was examined.
从容易获得的α-氨基酸开始,合成了几个2-取代的和2,5-二取代的哌嗪-3,6-二酮。通过将甲氧基羰基引入到氮上来活化内酰胺羰基后,该羰基被选择性地还原。用质子酸处理所得的氨基甲酸酯产生相应的N-酰基亚胺离子,其被亲核的C 2-侧链捕获,以提供2,6-桥连的哌嗪-3-酮。几个芳族,杂芳族和非芳族侧链被用作pi-亲核试剂。另外,检查了C 5-甲基的存在对环化的立体化学结果的影响。