Pd(II) Complexes Ligated by 1,3-Bis(diphenylphosphino)calix[4]arene: Preparation, X-ray Structures, and Catalyses

Pd(II) Complexes Ligated by 1,3-Bis(diphenylphosphino)calix[4]arene: Preparation, X-ray Structures, and Catalyses

Kengo Hirasawa, Shinya Tanaka*, Takeru Horiuchi, Takahiro Kobayashi, Takumi Sato, Naoya Morohashi, and Tetsutaro Hattori*
Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, 6-6-11 Aramaki-Aoba, Aoba-ku, Sendai 980-8579, Japan
Organometallics, Article ASAP
DOI: 10.1021/acs.organomet.5b00999
Publication Date (Web): January 22, 2016

syn-1,3-Bis(diphenylphosphino)-2,4-dimethoxycalix[4]arene (7) was synthesized via an Ullmann-type phosphinoylation of the syn-1,3-bis(triflate ester) (2) of p-tert-butylcalix[4]arene, followed by reduction of the phosphinoyl moieties and subsequent methylation of the remaining hydroxy groups. The treatment of diphosphine 7 with 2 molar equiv of PdCl2(MeCN)2 in benzonitrile afforded di-μ-chloro-bridged dinuclear palladium complex 8, formulated as Pd2(7)Cl4, whereas the same reaction conducted in acetonitrile with 1 molar equiv of PdCl2(MeCN)2 yielded mononuclear palladium complex 9, formulated as [Pd(7)Cl(MeCN)]Cl. Complex 9 was transformed into dicationic complex 11, formulated as [Pd(7) MeCN)2](BF4)2, by treatment with AgBF4 in dichloromethane, followed by the addition of acetonitrile. On the other hand, refluxing complex 9 in 1,2-dichloroethane yielded neutral complex 12, formulated as Pd(7)Cl2. In each of the mononuclear complexes, the palladium ion adopts a tetracoordinated square-planar geometry perpendicular to the mean plane defined by the macrocycle, and two phosphorus atoms occupy trans coordination sites. Consequently, an acetonitrile or chlorine ligand coordinates through the cavity of the calixarene, while another acetonitrile or chlorine ligand occupies the exo position. Dicationic complex 11 promoted Suzuki–Miyaura coupling between aryl chlorides and phenylboronic acid and the ring-opening reaction of an epoxide with thiophenol.

A steric tethering approach enables palladium-catalysed C–H activation of primary amino alcohols

Jonas Calleja, Daniel Pla, Timothy W. Gorman, Victoriano Domingo, Benjamin Haffemayer, & Matthew J. Gaunt

 

Nature Chemistry 7, 1009–1016  (2015)  doi:10.1038/nchem.2367    Received 27 May 2015             Accepted    02 September 2015     Published online 02 November 2015

Abstract      

Aliphatic primary amines are a class of chemical feedstock essential to the synthesis of higher-order nitrogen-containing molecules, commonly found in biologically active compounds and pharmaceutical agents. New methods for the construction of complex amines remain a continuous challenge to synthetic chemists. Here, we outline a general palladium-catalysed strategy for the functionalization of aliphatic C–H bonds within amino alcohols, an important class of small molecule. Central to this strategy is the temporary conversion of catalytically incompatible primary amino alcohols into hindered secondary amines that are capable of undergoing a sterically promoted palladium-catalysed C–H activation. Furthermore, a hydrogen bond between amine and catalyst intensifies interactions around the palladium and orients the aliphatic amine substituents in an ideal geometry for C–H activation. This catalytic method directly transforms simple, easily accessible amines into highly substituted, functionally concentrated and structurally diverse products, and can streamline the synthesis of biologically important amine-containing molecules.

http://www.nature.com/nchem/journal/v7/n12/full/nchem.2367.html

Recent developments in the preparation of N-heterocycles using Pd-catalyzed C-H activation

Recent developments in the preparation of N-heterocycles using Pd-catalyzed C-H activation
http://www.sciencedirect.com/science/article/pii/S0022328X15301935

Tanveer Mahamad Ali Shaikha, Fung-E. Honga

doi:10.1016/j.jorganchem.2015.10.022

Journal of Organometallic Chemistry, In Press, Accepted Manuscript

Abstract: The direct and selective activation of C-H bonds for the synthesis of N-heterocycles (C-N bonds) is an important areain modern synthetic chemistry due to its wide application in both in academics and industry. These compounds are frequently found as backbones in bioactive molecules and fine chemicals and are often used as organocatalysts or as auxiliary ligands in transition metal complexes assisted catalyses. Various kinds of palladium-containing complexes as active catalysts in the C(sp3)-H or C(sp2)-H bond activation have attracted increasing attention because of their accessibility and catalytic efficiencies. This review summarizes the recent developments in this area which employs Pd0-PdIV as versatile catalyst precursors to the syntheses of N-heterocycles. The N-heterocycles, including five- and six-membered rings, are described separately. Furthermore, some of the asymmetric C-H bond activation and mechanistic aspects of these catalytic reactions are discussed. 

Oxidative Coupling between Two Hydrocarbons: An Update of Recent C–H Functionalizations

Oxidative Coupling between Two Hydrocarbons: An Update of Recent C-H Functionalizations

Chao Liu,† Jiwen Yuan,† Meng Gao,‡ Shan Tang,† Wu Li,† Renyi Shi,† and Aiwen Lei*,†,‡

† College of Chemistry and Molecular Sciences, Institute for Advanced Studies (IAS), Wuhan University, Wuhan 430072, People’s Republic of China ‡ National Research Center for Carbohydrate Synthesis, Jiangxi Normal University, Nanchang, Jiangxi 330022, People’s Republic of China

Chemical Reviews; http://pubs.acs.org/doi/pdf/10.1021/cr500431s
DOI: 10.1021/cr500431s

Abstract: Somewhat comprehensive review of recent C-H functionalizations. Note this was received August 7, 2014.

Chemoselective Palladium-Catalyzed Deprotonative Arylation/[1,2]-Wittig Rearrangement of Pyridylmethyl Ethers

http://pubs.rsc.org/en/Content/ArticleLanding/2015/SC/C5SC02739J?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+rss%2FSC+%28RSC+-+Chem.+Sci.+latest+articles%29#!divAbstract


Chemoselective Palladium-Catalyzed Deprotonative Arylation/[1,2]-Wittig Rearrangement of Pyridylmethyl Ethers
Feng Gao, Byeong-Seon Kim and Patrick Walsh

Chem. Sci., 2015, Accepted Manuscript
DOI: 10.1039/C5SC02739J
Received 27 Jul 2015, Accepted 26 Oct 2015
First published online 27 Oct 2015


Control of chemoselectivity is one of the most challenging problems facing chemists and is particularly important in the synthesis of bioactive compounds and medications. Herein, the first highly chemoselective tandem C(sp3)–H arylation/[1,2]-Wittig rearrangement of pyridylmethyl ethers is presented. The efficient and operationally simple protocols enable generation of either arylation products or tandem arylation/[1,2]-Wittig rearrangement products with remarkable selectivity and good to excellent yields (60−99%). Choice of base, solvent, and reaction temperature play a pivotal role in tuning the reactivity of intermediates and controlling the relative rates of competing processes. The novel arylation step is catalyzed by a Pd(OAc)2/NIXANTPHOS-based system via a deprotonative cross-coupling process. The method provides rapid access to skeletally diverse aryl(pyridyl)methanol core structures, which are central components of several medications.

Homogeneous Pd catalysts on polymer supports for easy recovery and recycling

 http://www.sciencedirect.com/science/article/pii/S156673671530011X

An easily recoverable and recyclable homogeneous polyester-based Pd catalytic system for the hydrogenation of α,β-unsaturated carbonyl compounds

• Mattia Bartoli^a,
• Luca Rosi^{a, b},
• Giorgio Petrucci^a,
• Lidia Armelao^c,
• Werner Oberhauser^d,
• Marco Frediani^a, ,
• Oreste Piccolo^{e, f},
• Vikas Damu Rathod^e,
• Stefano Paganelli^{e, ,}

---

Highlights

•

trans-[Pd(OAc)₂(L)₂] was synthesized from Pd(OAc)₂ and the poly(l-lactide) (L).

•

trans-[Pd(OAc)₂(L)₂] was used as catalytic precursor in hydrogenations.

•

trans-[Pd(OAc)₂(L)₂] is a homogeneous catalytic precursor.

•

The homogeneous catalyst can be easily recovered from the reaction mixture.

•

The catalytic system maintained its activity in recycle experiments.

---

Abstract

Homogeneous catalysis is an efficient tool to carry out hydrogenation processes but the major drawback is represented by the separation of the expensive catalyst from the product mixture. In this view we prepared a polyester-based Pd catalytic system that offers the advantages of both homogenous and heterogeneous catalyses: efficacy, selectivity and recyclability. Here its application in the hydrogenation of selected α,β-unsaturated carbonyl compounds is described.

---

Graphical abstract