Structure-activity relationship of dihydroimidazo-, dihydropyrimido, tetrahydrodiazepino-[2,1-b]-thiazoles, and -benzothiazoles as an acylation catalyst

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• 作者：Sentaro Okamoto ; ^{okamos10@kanagawa-u.ac.jp" class="auth_mail} ; Yuzo Sakai ; Saki Watanabe ; Shohei Nishi ; Aya Yoneyama ; Hitomi Katsumata ; Yu Kosaki ; Rumi Sato ; Megumi Shiratori ; Misuzu Shibuno ; Tsukasa Shishido
• 关键词：Cyclic isothiourea ; Acylation ; Catalyst ; Substitution effect ; Kinetic resolution
• 刊名：Tetrahedron Letters
• 出版年：12 March, 2014
• 年：2014
• 卷：55
• 期：11
• 页码：1909-1912
• 全文大小：1101 K

文摘

Cyclic isothioureas class="boldFont">1, class="boldFont">2, class="boldFont">3, and class="boldFont">4 were synthesized through a four-step procedure from the corresponding ortho-bromoanilines class="boldFont">10 via Pd- or Cu-catalyzed cyclization-benzothiazole formation. Nonbenzo analogues class="boldFont">7, class="boldFont">8, and class="boldFont">9 were synthesized by a condensation reaction of cyclic thioureas class="boldFont">15 and 伪-bromoacetophenones class="boldFont">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 class="boldFont">3 and class="boldFont">7 were also studied.