Solid-supported barbituric acid can be used for the palladium(0)-catalyzeddeprotection of allyl amines, carbamates, carbonates, esters and ethers. This solid-supported reagent facilitates isolation and purification of the deprotected compounds. especially acids and amines.
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
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
of racemic and branched monosubstituted allylicacetates by a ruthenium-catalyzed regioselective allylic etherification. The reaction was effectively catalyzed by the chiral ruthenium catalyst, which was generated by [RuCl2(p-cymene)]2 and (S,S)-iPr-pybox and a catalytic amount of TFA, and both the allylic etherification product and recovered allylicacetate were obtained as an enantiomerically enriched
Iridium-Catalyzed Enantioselective Allylic Substitution of Enol Silanes from Vinylogous Esters and Amides
作者:Ming Chen、John F. Hartwig
DOI:10.1021/jacs.5b09980
日期:2015.11.4
silanes of vinylogous esters and amides are classic dienes for Diels-Alder reactions. Here, we report their reactivity as nucleophiles in Ir-catalyzed, enantioselective allylic substitution reactions. A variety of allylic carbonates react with these nucleophiles to give allylated products in good yields with high enantioselectivities and excellent branched-to-linear ratios. These reactions occur with
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。