Selectfluor-mediated mild oxidative halogenation and thiocyanation of 1-aryl-allenes with TMSX (X=Cl, Br, I, NCS) and NH4SCN
摘要:
Presence of TMSX (X = Cl, Br, I) unleashes the oxidative character of Selectfluor and provides a mild dihalogenation method for 1-arylallenes. Preference for 2,3-addition was observed with TMSCl in MeCN irrespective of the nature of the substituent on the aryl moiety, whereas 1,2-addition was preferred in [BMIM][BF4]. With TMSBr and TMSI only products corresponding to 2,3-addition were observed. Reactions carried out with TMSBr in IL solvents gave the corresponding monobromoalkenes as a major product along with the isomeric dibromo-alkenes. Reaction with NH4SCN provided convenient access to dithiocyanate derivatives. The same products were formed via TMS-NCS/Selectfluor. Formation of common products via TMSNCS and NH4SCN points to the formation and interplay of SCN+/NCS+ as incipient electrophiles. (C) 2014 Elsevier Ltd. All rights reserved.
An enantioselective alkoxycarbonylation-amination cascade process of terminalallenes with CO, methanol, and arylamines has been developed. It proceeds under mild conditions (room temperature, ambient pressure CO) via oxidative Pd(II) catalysis using an aromatic spiroketal-based diphosphine (SKP) as a chiral ligand and a Cu(II) salt as an oxidant and affords a wide range of α-methylene-β-arylamino
Palladium-Catalyzed Oxidative Carbonylative Coupling of Arylallenes, Arylboronic Acids, and Nitroarenes
作者:Hui-Qing Geng、Jin-Bao Peng、Xiao-Feng Wu
DOI:10.1021/acs.orglett.9b02925
日期:2019.10.18
In this Letter, a palladium-catalyzed multicomponent procedure for the selective synthesis of α-substituted α,β-unsaturated ketones has been developed. With readily available allenes, arylboronicacids, and nitroarenes as the substrates, the reaction proceeds selectively to the desired α-substituted enones. Notably, no manipulation of carbon monoxide gas is needed here, and Mo(CO)6 has been applied
A distinct copper-catalyzed boroacylation of allenes with acylchlorides and bis(pinacolato)diboron is developed. For aromatic acylchlorides, 1,2-boroacylation of allenes readily takes place, leading to the formation of tetrasubstituted vinylboronates with exclusive (E)-stereoselectivity. In comparison, the employment of alkyl acylchlorides as electrophiles alters the selectivity to 2,3-boroacylated
开发了一种独特的铜催化丙二烯与酰氯和双(频哪醇)二硼的硼酰化反应。对于芳族酰氯,丙二烯很容易发生 1,2-硼酰化,导致形成具有排他性 ( E )-立体选择性的四取代乙烯基硼酸酯。相比之下,使用烷基酰氯作为亲电试剂会改变对 2,3-硼酰化产物的选择性。此外,该产品可以很容易地进行 Suzuki-Miyaura 交叉偶联,得到完全保留构型的四取代烯烃。
Cobalt-Catalyzed C–H Activation and [3 + 2] Annulation with Allenes: Diastereoselective Synthesis of Indane Derivatives
作者:Arnab Dey、Chandra M. R. Volla
DOI:10.1021/acs.orglett.1c01521
日期:2021.7.2
ve [3 + 2] annulation reaction has been achieved, employing allenes as the annulation partners. The selective 2,3-migratory insertion of allenes with arylcobalt(III) species and the subsequent intramolecular diastereoselective nucleophilic addition of η1-allylcobalt onto the imine resulted in [3 + 2] annulation over the alternative [4 + 2] annulation. Furthermore, the oxidative annulation obviates
The dicarbonylation of 1,3‐butadiene to adipic acid derivatives offers the potential for a more cost‐efficient and environmentally benign industrial process. However, the complex reaction network of regioisomeric carbonylation and isomerization pathways, make a selective and direct transformation particularly difficult. Here, we report surprising solvent effects on this palladium‐catalysed process
将1,3-丁二烯二羰基化为己二酸衍生物可为更具成本效益和环境友好的工业生产提供潜力。然而,区域异构体羰基化和异构化途径的复杂反应网络使得选择性和直接转化特别困难。在这里,我们报道了在存在1,2-双-二叔丁基膦膦-二甲苯(d t bpx)配体的情况下,钯催化的这一过程产生了令人惊讶的溶剂影响,这些配体允许由1,3-丁二烯,碳形成己二酸酯二酯。一氧化碳和甲醇,在可扩展条件下具有97%的选择性和100%的原子经济性。在最佳条件下,可以以高至极好的收率获得各种1,2-和1,3-二烯的二酯和三酯。