Copper/Silver-Cocatalyzed Conia−Ene Reactions of 2-Alkynic 1,3-Dicarbonyl Compounds
作者:Chen-Liang Deng、Tao Zou、Zhi-Qiang Wang、Ren-Jie Song、Jin-Heng Li
DOI:10.1021/jo802133w
日期:2009.1.2
A copper/silver-catalyzed Conia−enereaction has been developed for selectively constructing five-membered and six-membered rings. In the presence of (CuOTf)2·C6H6 and AgBF4, a variety of 2-alkynic 1,3-dicarbonylcompounds underwent the Conia−ene intramolecular reaction smoothly in moderate to good yields. It is noteworthy that both 2-phenylacetylhept-6-ynenitrile and diethyl 2-(pent-4-ynyl)malonate
已经开发出铜/银催化的Conia-ene反应,用于选择性地构建五元环和六元环。在(CuOTf)2 ·C 6 H 6和AgBF 4的存在下,各种2-炔基1,3-二羰基化合物顺利进行了Conia-ene分子内反应,产率中等至良好。值得注意的是,在标准条件下,2-苯基乙酰庚基-6腈和2-(戊-4-炔基)丙二酸二乙酯也是合适的底物,对内-或外-产物的选择性取决于末端的取代基。炔烃。
Iodobenzene-Catalyzed Intramolecular Oxidative Cyclization Reactions of δ-Alkynyl β-Ketoesters
作者:Arantxa Rodríguez、Wesley J. Moran
DOI:10.1021/ol200471w
日期:2011.5.6
Iodobenzene is shown to catalyze the 5-exo-dig cyclization of δ-alkynyl β-ketoesters under oxidative conditions that generatehypervalentiodinespecies in situ. The cyclopentane products contain adjacent quaternary and tertiary stereocenters which are generated with excellent diastereoselectivity.
the gold(I)‐catalyzed Conia‐ene cyclization of ϵ‐acetylenic‐β‐ketoesters bearing an internal alkyne moiety was investigated for the first time. The reaction catalyzed by commercially available PPh3AuNTf2 complex, which is sluggish at ambient pressure owing to steric reasons, proceeds smoothly under high‐pressure conditions (6 kbar). Mechanistic aspects of the reaction proceeding via 5‐exo‐dig and 6‐endo‐dig
A cationic gold(l) complex with a semihollow-shaped trialkynylphosphine catalyzed 5-exo-dig and 6-endo-dig cyclizations of various internal alkynic beta-keto esters, showing a marked advantage over a gold(I)-PPh3 complex with respect to the rates of the reactions and the product yields. It is proposed that the gold-bound alkynic substrate in a catalytic pocket must be somewhat folded and that such a steric effect makes the carbon-carbon bond formation entropically more favorable.
New Cobalt-Catalyzed Cycloisomerization of ε-Acetylenic β-Keto Esters. Application to a Powerful Cyclization Reactions Cascade
type reaction of epsilon-acetylenic beta-keto esters to form highly functionalized methylenecyclopentanes are described. The observed regio-, chemo-, and stereoselectivities support a process of cycloisomerization which controls the relative stereochemistry of two contiguous stereogenic centers. An efficient route to the basic skeleton of the phyllocladane family has been achieved via a one-pot sequence