Application of palladium complexes bearing acyclic amino(hydrazido)carbene ligands as catalysts for copper-free Sonogashira cross-coupling



Timofeeva, Svetlana A, Kinzhalov, Mikhail A, Valishina, Elena A, Luzyanin, Konstantin V ORCID: 0000-0001-9312-7139, Boyarskiy, Vadim P, Buslaeva, Tatyana M, Haukka, Matti and Kukushkin, Vadim Yu
(2015) Application of palladium complexes bearing acyclic amino(hydrazido)carbene ligands as catalysts for copper-free Sonogashira cross-coupling. JOURNAL OF CATALYSIS, 329. pp. 449-456.

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Abstract

Abstract Metal-mediated coupling of one isocyanide in cis-[PdCl<inf>2</inf>(CNR<sup>1</sup>)<inf>2</inf>] (R<sup>1</sup> = C<inf>6</inf>H<inf>11</inf> (Cy) 1, tBu 2, 2,6-Me<inf>2</inf>C<inf>6</inf>H<inf>3</inf> (Xyl) 3, 2-Cl-6-MeC<inf>6</inf>H<inf>3</inf> 4) and various carbohydrazides R<sup>2</sup>CONHNH<inf>2</inf> [R<sup>2</sup> = Ph 5, 4-ClC<inf>6</inf>H<inf>4</inf> 6, 3-NO<inf>2</inf>C<inf>6</inf>H<inf>4</inf> 7, 4-NO<inf>2</inf>C<inf>6</inf>H<inf>4</inf> 8, 4-CH<inf>3</inf>C<inf>6</inf>H<inf>4</inf> 9, 3,4-(MeO)<inf>2</inf>C<inf>6</inf>H<inf>3</inf> 10, naphth-1-yl 11, fur-2-yl 12, 4-NO<inf>2</inf>C<inf>6</inf>H<inf>4</inf>CH<inf>2</inf> 13, Cy 14, 1-(4-fluorophenyl)-5-oxopyrrolidine-3-yl 15, (pyrrolidin-1-yl)C(O) 16, 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propane-1-yl 17, EtNHC(O) 18] or sulfohydrazides R<sup>3</sup>SO<inf>2</inf>NHNH<inf>2</inf> [R<sup>3</sup> = Ph 19, 4-MeC<inf>6</inf>H<inf>4</inf> 20] led to a series of (hydrazido)(amino)carbene complexes cis-[PdCl<inf>2</inf>{C(NHNHX)N(H)R<sup>1</sup>}(CNR<sup>1</sup>)]; X = COR<sup>2</sup>, SO<inf>2</inf>R<sup>3</sup> (21-48, isolated yields 60-96%). All prepared species were characterized by elemental analyses (C, H, N), HR ESI<sup>+</sup>-MS, IR, <sup>1</sup>H and <sup>13</sup>C{<sup>1</sup>H} NMR spectroscopy, and by a single-crystal X-ray diffraction for 38. Complexes 21-48 demonstrated excellent activity as catalysts in copper-free Sonogashira coupling of aryl iodides and a variety of aromatic terminal alkynes. Catalytic system runs in environmentally benign EtOH ensuring product yields of up to 75-96% and TONs of up to 10<sup>4</sup>. Mechanism of the copper-free Sonogashira catalytic cycle involving 21-48 as catalysts was proposed upon identification of key intermediates using HRESI-mass.

Item Type: Article
Uncontrolled Keywords: Acyclic diaminocarbenes, Palladium-(acyclic diminocarbene) catalysts, Copper-free Sonogashira coupling, Mechanism of catalytic action of Pd-ADCs
Depositing User: Symplectic Admin
Date Deposited: 18 Aug 2016 14:17
Last Modified: 19 Jan 2023 07:32
DOI: 10.1016/j.jcat.2015.06.001
Related URLs:
URI: https://livrepository.liverpool.ac.uk/id/eprint/3002978