Umpolung cyclization reaction of <i>N</i>-cinnamoylthioureas in the presence of DBU
作者:Rei Saito、Naohiro Uemura、Hiroki Ishikawa、Akina Magara、Yasushi Yoshida、Takashi Mino、Yoshio Kasashima、Masami Sakamoto
DOI:10.1039/c8ob02066c
日期:——
A novel regioselective cyclization reaction of N-cinnamoylthioureas leading to six- or five-membered heterocyclic compounds was developed. N-Cinnamoylthioureas in the presence of trifluoroacetic acid (TFA) underwent the well-established intramolecular cycloaddition reaction to give 2-imino-2,3,5,6-tetrahydro-4H-1,3-thiazin-4-ones in good yields. On the other hand, the reaction with 1,8-diazabicyclo[5
开发了导致六元或五元杂环化合物的N-肉桂酰基硫脲的新的区域选择性环化反应。在三氟乙酸(TFA)存在下对N-肉桂酰硫脲进行完善的分子内环加成反应,得到2-亚氨基-2,3,5,6-四氢-4 H -1,3-噻嗪-4-酮产量。另一方面,与1,8-二氮杂双环[5.4.0]十一碳-7-烯(DBU)的反应以空前的“ umpolung”环化方式进行,得到了五元的2-亚氨基-1,3-噻唑烷酮- 4-酮和/或2-硫代氧杂咪唑烷-4-酮。该反应被认为是通过DBU与肉桂酰基部分的环加合物发生的,然后是硫脲基团的分子内攻击。