Adducts of t-butyl-substituted diphosphines with triflic acid: Synthesis, characterization and application to Pd-catalyzed methoxycarbonylation-aminolysis tandem reaction

Synthesis of linear primary amides via methoxycarbonylation-aminolysis tandem reaction. [Display omitted] •Methoxycarbonylation-aminolysis tandem reaction for synthesis of linear primary amides.•Base-acid adduct of A derived from DTBPMB and HOTf as a moisture/oxygen insensitive ionic compound.•A-mod...

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Published in:Journal of catalysis 2024-01, Vol.429, p.115200, Article 115200
Main Authors: Chen, Xiao-Chao, Shi, Guang-Hui, Jing, Tian-Hong, Zhuang, Yi-Ying, Zhao, Xiao-Li, Lu, Yong, Liu, Ye
Format: Article
Language:English
Subjects:
Acid-base adducts
Aminolysis
Lewis basic phosphines
Methoxycarbonylation
Primary amides: Carbonylation
Tandem reaction
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Summary:Synthesis of linear primary amides via methoxycarbonylation-aminolysis tandem reaction. [Display omitted] •Methoxycarbonylation-aminolysis tandem reaction for synthesis of linear primary amides.•Base-acid adduct of A derived from DTBPMB and HOTf as a moisture/oxygen insensitive ionic compound.•A-modified Pd(OAc)2 catalyst exhibiting remarkable performance for methoxycarbonylation-aminolysis tandem reaction. The acid-base adducts (A and B) as the ionic salts in the format of [L-2H]2+[OTf]2−, derived from the neutralization of t-butyl-substituted diphosphines [L1: 1,2-bis[(di-tert-butylphosphanyl)methyl]benzene; L2: 4,5-bis(di-tert-butylphosphino)-9,9-dimethylxanthene] with triflic acid (HOTf, CF3SO3H), were synthesized, characterized, and then applied in Pd-catalyzed methoxycarbonylation-aminolysis tandem reaction for the synthesis of linear primary amides. For the first time, the structural configurations of such adducts were deconvoluted by the single crystal X-ray diffraction analysis. In A, the two P-H bonds were distinct, and one of the P-H bond was hydrogen-bonded with CF3SO3−-anion whereas the two P-H bonds in B were equivalent without hydrogen-bond effect. A became more robust against moisture and oxygen than its counterpart of L1 due to the available hydrogen-bond interaction whereas B became more labile in comparison to L2. When A was applied in Pd-catalyzed methoxycarbonylation-aminolysis tandem reaction, the linear primary amides were obtained in the yields of 69–84% whereas B led to the poor result. It was found that A-Pd(OAc)2 system not only successfully catalyzed the first-step methoxycarbonylation of alkenes to generate the carboxylic esters with L/B > 90/10 by predominantly following anti-Markovnikov’s rule, but also accelerated the second-step aminolysis.
ISSN:0021-9517
1090-2694
DOI:10.1016/j.jcat.2023.115200