Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive East, Los Angeles, California 90095-1569, USA.
Org Lett. 2011 Oct 21;13(20):5420-3. doi: 10.1021/ol201730q. Epub 2011 Sep 20.
General base-catalyzed double-Michael reactions of allenes with various dinucleophiles are described. The reactions are facilitated most efficiently by a catalytic amount of trimethylphosphine, affording six types of C2-functionalized benzannulated five-membered heterocycles: benzimidazolines, benzoxazolines, benzothiazolines, 1,3-benzodioxoles, 1,3-benzoxathioles, and 1,3-benzodithioles. This atom-economical reaction is operationally simple and provides the product heterocycles in good to excellent yields. Careful mechanistic studies unveiled the phosphine-triggered general base catalysis pathway. Furthermore, the double-Michael reaction can serve as an alternative method for the selective monoketalization of β-diketones.
本文描述了各类二亲核试剂与丙二烯的通用碱催化的双迈克尔加成反应。反应在催化量三甲基膦的促进下最为有效,生成了 6 种 C2 功能化的苯并稠合五元杂环化合物:苯并咪唑啉、苯并恶唑啉、苯并噻唑啉、1,3-苯并二氧戊环、1,3-苯并噻吩和 1,3-苯并二硫戊环。该原子经济性反应操作简单,以良好至优秀的收率得到产物杂环。通过仔细的机理研究揭示了三甲基膦引发的通用碱催化途径。此外,双迈克尔加成反应可作为β-二酮选择性单缩酮化的替代方法。