Diphosphino-Functionalized MCM-41-Immobilized Rhodium Complex: A Highly Efficient and Recyclable Catalyst for the Hydrop
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Diphosphino-Functionalized MCM-41-Immobilized Rhodium Complex: A Highly Efficient and Recyclable Catalyst for the Hydrophosphinylation of Terminal Alkynes Fang Yao • Jian Peng • Wenyan Hao Mingzhong Cai
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Received: 12 December 2011 / Accepted: 30 January 2012 / Published online: 4 April 2012 Ó Springer Science+Business Media, LLC 2012
Abstract Diphosphino-functionalized MCM-41-immobilized rhodium complex (MCM-41-2P-RhCl3) was conveniently synthesized from commercially available and cheap c-aminopropyltriethoxysilane via immobilization on mesoporous MCM-41, followed by reacting with diphenylphosphinomethanol and rhodium chloride. It was found that this heterogeneous rhodium complex is a highly efficient catalyst for the hydrophosphinylation of terminal alkynes with diphenylphosphine oxide and can be recovered and recycled by a simple filtration of the reaction solution and used for at least 10 consecutive trials without any decreases in activity. Keywords Supported rhodium catalyst Functionalized MCM-41 Phosphine rhodium complex Hydrophosphinylation Heterogeneous catalysis
1 Introduction Alkenylphosphine oxides are key synthetic intermediates for the preparation of various phosphine ligands and present in numerous biologically active products [1–6]. In addition, a variety of heteroatom nucleophiles such as alcohols [7], thiols [8], primary and secondary amines [9–11], and phosphines [12] readily add to the double bond in F. Yao J. Peng W. Hao M. Cai (&) Department of Chemistry, Jiangxi Normal University, Nanchang 330022, People’s Republic of China e-mail: [email protected] F. Yao Department of Chemistry and Pharmaceutical Engineering, West Branch of Zhejiang University of Technology, Quzhou 324000, People’s Republic of China
alkenylphosphine oxides to afford versatile bifunctional compounds, which allow further synthetic transformations. Alkenylphosphine oxides have also been used for the formation of carbon–carbon bond via reactions with carbanion species [13] or carbon-centered radicals [14, 15]. Transitionmetal-catalyzed addition of an P–H bond to alkynes is a straightforward method for the generation of alkenylphosphorus compounds [16–20], but this transformation always results in a mixture of E/Z configurations, and it is difficult to obtain one single product. Han et al. [21] described a rhodium-catalyzed regio- and stereoselective hydrophosphinylation of alkynes with Ph2P(O)H, which provides a new convenient and clean method for the preparation of (E)-alkenylphosphine oxides. However, industrial applications of homogeneous rhodium complexes remain a challenge because they are expensive, cannot be recycled, and difficult to separate from the product mixture, which is a particularly significant drawback for their application in the pharmaceutical industry. The immobilization of catalytically active species, i.e., organometallic complexes, onto a solid support to produce a molecular heterogeneous catalyst is one potential solution to the latter two problems [22]. The high costs of the transition
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