Efficient and Systematic Click-Based Synthetic Routes to Amino Acid Functionalized Metallatricarbadecaboranes

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• 作者：Ariane Perez-Gavilan ; Patrick J. Carroll ; Larry G. Sneddon
• 刊名：Organometallics
• 出版年：2012
• 出版时间：April 9, 2012
• 年：2012
• 卷：31
• 期：7
• 页码：2741-2748
• 全文大小：378K
• 年卷期：v.31,no.7(April 9, 2012)
• ISSN：1520-6041

文摘

A general method for the systematic syntheses of amino acid functionalized metallatricarbadecaboranyl complexes has been developed that employs the copper-catalyzed click addition reactions of N-azidoacetyl amino acid methyl esters to a p-ethynylphenyl substituent at a cage carbon of the metallatricarbadecaboranyl cage. The trimethylsilyl-protected p-ethynylphenyl Li⁺[6-(p-((CH₃)₃SiC鈮)C₆H₄)-nido-5,6,9-C₃B₇H₉^{鈥?/sup>] (1) tricarbadecaboranyl anion was synthesized via the reaction of arachno-4,6-C₂B₇H₁₂鈥?/sup> with p-((CH₃)₃SiC鈮)C₆H₅CN. Reaction of 1 with (畏5-C₅H₅)Fe(CO)₂I and (畏5-C₅H₅)Ru(CH₃CN)₃PF₆ produced 1-(畏5-C₅H₅)-2-(p-((CH₃)₃SiC鈮)C₆H₄)-closo-1,2,3,4-MC₃B₇H₉ (M = Fe (2), Ru (3)). Deprotection of 2 and 3 with K₂CO₃ in MeOH/THF afforded the ethynyl derivatives 1-(畏5-C₅H₅)-2-(p-(HC鈮)C₆H₄)-closo-1,2,3,4-MC₃B₇H₉ (M = Fe (4), Ru (5)). Click addition of the model compound benzyl azide to 4 and 5 to form the triazole complexes, 1-(畏5-C₅H₅)-2-(p-(1-(C₆H₅CH₂)-1H-1,2,3-N₃C₂-4-)C₆H₄)-closo-1,2,3,4-MC₃B₇H₉ (M = Fe (6), Ru (7)) confirmed the reactivity of the p-ethynyl group toward copper-catalyzed click azide addition, with the triazole-linked structure of 7 crystallographically established. Subsequent click addition reactions of the N-azidoacetyl amino acid methyl esters to 4 yielded a wide range of amino acid functionalized ferratricarbadecaboranyl complexes: 1-(畏5-C₅H₅)-2-(p-(1-(Xaa-C(O)CH₂)-1H-1,2,3-N₃C₂-4-)C₆H₄)-closo-1,2,3,4-FeC₃B₇H₉ (Xaa = PheOMe (8), LeuOMe (9), ValOMe (10), MetOMe (11), AlaOMe (12), TryOMe (13)).}