乙烯基酯和酰胺的烯醇硅烷是 Diels-Alder 反应的经典二烯。在这里,我们报告了它们在 Ir 催化的对映选择性烯丙基取代反应中作为亲核试剂的反应性。各种烯丙基碳酸酯与这些亲核试剂反应,以良好的收率和高对映选择性和出色的支链与线性比率得到烯丙基化产物。这些反应以 KF 或醇盐作为添加剂发生,但机理研究表明这些添加剂不会激活烯醇硅烷。相反,它们用作促进环金属化以生成活性 Ir 催化剂的碱。由烯丙基碳酸酯的氧化加成产生的碳酸根阴离子可能会激活烯醇硅烷以触发它们作为亲核试剂与烯丙基铱亲电试剂反应的活性。
Rhodium-Catalyzed Asymmetric N−H Functionalization of Quinazolinones with Allenes and Allylic Carbonates: The First Enantioselective Formal Total Synthesis of (−)-Chaetominine
作者:Yirong Zhou、Bernhard Breit
DOI:10.1002/chem.201705059
日期:2017.12.22
An unprecedented asymmetric N−H functionalization of quinazolinones with allenes and allylic carbonates was successfully achieved by rhodium catalysis with the assistance of chiral bidentate diphosphine ligands. The high efficiency and practicality of this method was demonstrated by a low catalyst loading of 1 mol % as well as excellent chemo‐, regio‐, and enantioselectivities with broad functional
Ï-Allylic azidation of allyl esters was performed with an amphiphilic polystyrene-poly(ethylene glycol) (PS-PEG) resin-supported phosphine-palladium complex in water under heterogeneous conditions to give allyl azides in good to high yields. The polymeric palladium catalyst can be readily recovered and recycled.
electron-deficient imines with allylic alcohol derivatives in the presence of a catalytic amount of palladium(0) complex and indium(I) iodide was studied. The reversibility of allylation was observed in the reaction of glyoxylic oxime ether having camphorsultam. As the important effect of water on regioselectivity, the gamma-adducts were kinetically formed from monosubstituted allylic reagents in the presence
Co‐catalyzedallylic substitution reactions have received little attention, arguably because of the lack of any known advantage of Co catalysis over either Rh or Ir catalysis. Described here is a general and regioselective Co‐catalyzedallylicalkylation using an in situ catalyst activation by organophotoredox catalysis. This noble‐metal‐free catalytic system exhibits unprecedentedly high reactivities