Department of Chemistry, University of Rochester, Rochester, New York 14627, USA.
J Am Chem Soc. 2012 Oct 10;134(40):16551-3. doi: 10.1021/ja308451y. Epub 2012 Sep 28.
Dienyl diketones containing tethered acetates selectively undergo two different 1,6-conjugate addition-initiated cyclization cascades. One is a 1,6-conjugate addition/cyclization sequence with incorporation of the nucleophile, and the other is catalyzed by DABCO and is thought to proceed via a cyclic acetoxonium intermediate. The reaction behavior of substrates lacking the tethered acetate was also studied. The scope of both types of cyclization cascades, the role of the amine additive, and the factors controlling reactivity and selectivity in the two different reaction pathways is discussed.
二烯基二酮含有连接的乙酸酯,可选择性地经历两种不同的 1,6-共轭加成引发的环化级联反应。一种是带有亲核试剂的 1,6-共轭加成/环化序列,另一种是由 DABCO 催化,被认为通过环状乙酰氧鎓中间体进行。还研究了缺乏连接乙酸酯的底物的反应行为。讨论了两种环化级联的范围、胺添加剂的作用以及控制两种不同反应途径中反应性和选择性的因素。