40647-89-0Relevant articles and documents
Structure-activity relationship of dihydroimidazo-, dihydropyrimido, tetrahydrodiazepino-[2,1-b]-thiazoles, and -benzothiazoles as an acylation catalyst
Okamoto, Sentaro,Sakai, Yuzo,Watanabe, Saki,Nishi, Shohei,Yoneyama, Aya,Katsumata, Hitomi,Kosaki, Yu,Sato, Rumi,Shiratori, Megumi,Shibuno, Misuzu,Shishido, Tsukasa
, p. 1909 - 1912 (2014/03/21)
Cyclic isothioureas 1, 2, 3, and 4 were synthesized through a four-step procedure from the corresponding ortho-bromoanilines 10 via Pd- or Cu-catalyzed cyclization-benzothiazole formation. Nonbenzo analogues 7, 8, and 9 were synthesized by a condensation reaction of cyclic thioureas 15 and α-bromoacetophenones 14. Investigations of the acylation reactions of 1-phenylethanol with acid anhydrides in the presence of these cyclic isothiourea catalysts revealed their structure-activity relationships. Remarkable electronic effects resulting from substituent(s) on a benzo or phenyl moiety and the influence of the size of the annulating ring were observed. Introduction of an electron-donating substituent(s) enhanced the reaction rate. A few substitution effects on chiral catalysts of type 3 and 7 were also studied.
