General and Versatile Entry to 4,5-Fused Polycyclic Imidazolones Systems. Use of the Tandem Transposition/π-Cyclization of <i>N</i>-Acyliminium Species
作者:Anthony Pesquet、Adam Daïch、Luc Van Hijfte
DOI:10.1021/jo060616s
日期:2006.7.1
A simple and efficient methodology for the synthesis of 4,5-fused imidazolidin-2-ones from bicyclic and tricyclic ketones in a four-step sequence was described, by successive spirohydantoin Bucherer−Berg formation, mono- and dialkylation of the nitrogen atom of the hydantoin ring, regioselective reduction of one carbonyl function, and cationic cyclization associated with ring expansion. The key step