Homogeneous and Heterogeneous Pd-Catalyzed Selective C-P Activation and Transfer Hydrogenation for "Group-Substitution" Synthesis of Trivalent Phosphines
Ming Lei, Xingyu Chen, Yingjie Wang, Liran Zhang, Hong Zhu* and Zhiqian Wang*
*State Key Laboratory of Chemical Resource Engineering, College of Chemistry, Beijing University of Chemical Technology, Beijing 100029, China,
Email: zhuho128126.com, wangzhq
mail.buct.edu.cn
M. Lei, X. Chen, Y. Wang, L. Zhang, H. Zhu, Z. Wang, Org. Lett., 2022, 24, 2868-2872.
DOI: 10.1021/acs.orglett.2c00844
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Abstract
C-P activation of phosphonium salts enables a "group-substitution" synthesis of trivalent phosphines. An alkylation of phosphines to provide phosphonium salts is followed by a Pd-catalyzed "de-arylation" via C-P activation and transfer hydrogenation. With this method, a series of trivalent phosphines were prepared from commercially available triarylphosphines.
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Details
The document discusses a novel "group-substitution" synthesis method for trivalent phosphines via C−P activation of phosphonium salts, facilitated by homogeneous and heterogeneous Pd(0) catalysts. The process involves alkylation of phosphines to form phosphonium salts, followed by C−P activation and transfer hydrogenation to produce alkyl diarylphosphines. This method allows for the preparation of various trivalent phosphines from commercially available triarylphosphines, including chiral monophosphine ligands from BINAP. The study highlights the high reactivity of Pd(0) catalysts, with Pd2(dba)3 and Pd/C showing significant yields under optimized conditions. The method tolerates various functional groups and sterically hindered substitutions, making it versatile for different phosphonium substrates. The research also explores the selectivity of C−P activation between different aryl groups, finding that steric effects play a significant role. The findings suggest that triarylphosphines can serve as surrogates for secondary phosphines in generating diversely substituted phosphines. The work demonstrates a practical synthesis pathway for trivalent phosphines and reveals the potential of C−P activation in organic synthesis.
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ID: J54-Y2022