Imidazolyl-PTA Derivatives as Water-Soluble (P,N) Ligands for Ruthenium-Catalyzed Hydrogenations

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• 作者：Donald A. Krogstad ; Antonella Guerriero ; Andrea Ienco ; Gabriele Manca ; Maurizio Peruzzini ; Gianna Reginato ; Luca Gonsalvi
• 刊名：Organometallics
• 出版年：2011
• 出版时间：November 28, 2011
• 年：2011
• 卷：30
• 期：22
• 页码：6292-6302
• 全文大小：492K
• 年卷期：v.30,no.22(November 28, 2011)
• ISSN：1520-6041

文摘

The first imidazolyl 鈥渦pper-rim鈥?derivatives of 1,3,5-triaza-7-phoshaadamantane (PTA), namely, 1-methylimidazolyl-(1,3,5-triaza-7-phosphatricyclo[3.3.1.1^3,7]dec-6-yl)methanol (2, PTA-CH(1-MeIm)OH) and bis(1-methylimidazolyl)(1,3,5-triaza-7-phosphatricyclo[3.3.1.1^3,7]dec-6-yl)methanol (3, PTA-C(1-MeIm)₂OH), were synthesized in fair yields by reaction of PTA-Li with 1-methyl-2-imidazole carboxyaldehyde and bis(N-methylimidazole-2-yl) ketone, respectively. Compounds 2 and 3 exhibit higher water solubility than most upper-rim derivatives of PTA. The two ligands reacted cleanly with [Ru(畏⁶-p-cymene)Cl₂]₂ in refluxing CHCl₃ to form 魏²-P,N-[(畏⁶-p-cymene)Ru{PTA-CH(1-MeIm)OH}Cl]Cl (8) and 魏²-P,N-[(畏⁶-p-cymene)Ru{PTA-C(1-MeIm)₂OH}Cl]Cl (9). Ligands phenyl(1,3,5-triaza-7-phosphatricyclo[3.3.1.1^3,7]dec-6-yl)methanol (PZA) and 4鈥?dimethylaminophenyl(1,3,5-triaza-7-phosphatricyclo[3.3.1.1^3,7]dec-6-yl)methanol (PZA-NMe₂) were also used to coordinate to Ru, and the corresponding 魏¹-P-[(畏⁶-p-cymene)Ru(PZA)Cl₂] (6) and 魏¹-P-[(畏⁶-p-cymene)Ru(PZA-NMe₂)Cl₂] (7) were isolated and characterized. The ability of the ligands to coordinate in 魏¹-P vs 魏²-P,E (E = O, N) modes was established by NMR experiments and complemented by DFT calculations. The X-ray crystal structure of the iodide analogue of 7 was obtained. Complexes 6鈥?b>9 were tested as catalysts for acetophenone reduction using different hydrogen sources under mild conditions, and preliminary results are here described.