Phosphine-Initiated General Base Catalysis: Facile Access to Benzannulated 1,3-Diheteroatom Five-Membered Rings via Double-Michael Reactions of Allenes
作者:Judy Szeto、Vardhineedi Sriramurthy、Ohyun Kwon
DOI:10.1021/ol201730q
日期:2011.10.21
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
描述了丙二烯与各种双亲核试剂的一般碱催化双迈克尔反应。催化量的三甲基膦可最有效地促进反应,提供六种类型的 C2 官能化苯并环化五元杂环:苯并咪唑啉、苯并恶唑啉、苯并噻唑啉、1,3-苯并二恶唑、1,3-苯并恶唑和 1,3-苯并二硫醇. 这种原子经济的反应在操作上很简单,并以良好到极好的收率提供产物杂环。仔细的机理研究揭示了膦触发的一般碱催化途径。此外,双迈克尔反应可以作为β-二酮选择性单缩酮化的替代方法。