Novel synthesis of dihydropyrans and 2,8-dioxabicylo[3.3.0]oct-3-enes using Mn(III)-based oxidative cyclization
作者:Van-Ha Nguyen、Hiroshi Nishino
DOI:10.1016/j.tetlet.2004.03.019
日期:2004.4
The Mn(III)-based reaction of 1,1-disubstituted alkenes with 2-(2-oxoethyl)malonates and 3-acetylpentane-1,4-diones gave novel substituted dihydropyrans and 2,8-dioxabicyclo[3.3.0]oct-3-enes in good yields, respectively. These routes rely on the nucleophilic character of the carbonyl-oxygen atoms of the malonates and pentanediones used to obtain the products by a cycloaddition reaction or cycloaddition–tandem
1,1-二取代的烯烃与2-(2-氧乙基)丙二酸酯和3-乙酰基戊烷-1,4-二酮的Mn(III)基反应产生了新的取代的二氢吡喃和2,8-二氧杂双环[3.3.0] oct -3-烯分别具有良好的收率。这些路线取决于丙二酸和戊二酮的羰基-氧原子的亲核特性,这些丙二酸和戊二酮用于通过环加成反应或环加成-串联环化反应获得产物。
Palladium‐Catalyzed (5+3) Annulation of 4‐Vinyl‐4‐Butyrolactones with C,N‐Cyclic Azomethine Imines: Construction of Eight‐Membered Ring
In this paper, we designed and synthesized 4-vinyl-4-butyrolactone as a precursor to generate the zwitterionicallylpalladiumintermediates, which behaved as five-membered all-carbon synthon in palladium-catalyzed (5+3) annulation with azomethineimines, giving eight-membered ring-fused heterocycles (26 examples, 49% to 97% yield, >20:1 dr).