Liyanage Perera Erandi, Wink Donald J, Luo Yanshu, Xia Yuanzhi, Lee Daesung
Department of Chemistry, University of Illinois Chicago, 845 West Taylor Street, Chicago, Illinois 60607, United States.
College of Chemistry and Materials Engineering, Wenzhou University, 325035 Wenzhou, Zhejiang, P. R. China.
J Org Chem. 2024 Apr 5;89(7):4496-4502. doi: 10.1021/acs.joc.3c02711. Epub 2024 Mar 20.
Acyl ketenes react with polar unsaturated functional groups to give unique heterocyclic rings, yet reactions with unpolarized unsaturated functional groups have not been reported. Herein, we describe two effective ring-forming reactions between acetyl ketene and electron-deficient alkynes. The first reaction involves in situ tethering between acetyl ketene and nucleophile-containing 1,3-diynones, which promotes sequential intramolecular 1,6/1,4-additions to generate 2-methylene-2-pyrans in various yields (24-91%). The other involves a zwitterionic intermediate generated from acetyl ketene and DABCO, which undergoes a Michael addition with terminal alkynyl ketones to generate 3-acyl-4-pyrones (11-79%).
酰基烯酮与极性不饱和官能团反应生成独特的杂环，但与非极性不饱和官能团的反应尚未见报道。在此，我们描述了乙酰基烯酮与缺电子炔烃之间的两种有效的成环反应。第一个反应涉及乙酰基烯酮与含亲核试剂的1,3 - 二炔酮之间的原位连接，促进分子内1,6/1,4 - 加成反应顺序进行，以不同产率（24 - 91%）生成2 - 亚甲基 - 2 - 吡喃。另一个反应涉及由乙酰基烯酮和1,4 - 二氮杂双环[2.2.2]辛烷（DABCO）生成的两性离子中间体，该中间体与末端炔基酮发生迈克尔加成反应生成3 - 酰基 - 4 - 吡喃（产率11 - 79%）。
