Osmium Models of Intermediates Involved in Catalytic Reactions of Alkylidenecyclopropanes

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• 作者：Miguel A. Esteruelas ; Ana M. L贸pez ; Fernando L贸pez ; Jos茅 L. Mascare帽as ; Silvia Mozo ; Enrique O帽ate ; Lucı ; ́ ; a Saya
• 刊名：Organometallics
• 出版年：2013
• 出版时间：September 9, 2013
• 年：2013
• 卷：32
• 期：17
• 页码：4851-4861
• 全文大小：664K
• 年卷期：v.32,no.17(September 9, 2013)
• ISSN：1520-6041

文摘

The complex [OsCp{魏³-<i>Pi>,<i>Ci>,<i>Ci>-PⁱPr₂[C(CH₃)鈺怌H₂]}(CH₃CN)]PF₆ (1) reacts with (2-pyridyl)methylenecyclopropane, at room temperature, to give initially the cyclobutylidene derivative [Os(畏⁵-C₅H₅)(鈺?img src="/templates/jsp/_style2/_achs/images/tiebar-below-start.gif" class="tbBelow" alt="tiebar below start"/>CCH₂CH₂CH-<i>oi>-C₅H₄N){PⁱPr₂[C(Me)鈺怌H₂]}]PF₆ (2), as a result of the ring expansion of the alkylidenecyclopropane unit. Over time complex 2 rearranges into the cyclobutene derivative [Os(畏⁵-C₅H₅){畏²-C(鈺怌HCH₂CH₂)-<i>oi>-C₅H₄N}{PⁱPr₂[C(Me)鈺怌H₂]}]PF₆ (3). The reaction of 1 with (2-pyridyl)methylenecyclopropane at room temperature also affords the phosphinomethanide metallacycle [Os(畏⁵-C₅H₅){魏⁴-<i>Pi>,<i>Ci>^a,<i>Ci>^b,<i>Ni>-PⁱPr₂[C^a(Me)CH₂CH)(C^bCH₂CH₂-<i>oi>-C₅H₄N]}]PF₆ (4) as a minor product, which becomes the major product of the reaction at 45 掳C. This osmacyclopentane results from the C鈥揅 coupling of the isopropenyl substituent of the phosphine ligand and the organic substrate. In acetone at 75 掳C, the reaction of 1 with (2-pyridyl)methylenecyclopropane leads to the 2-alkylidene-1-osmacyclobutane [Os(畏⁵-C₅H₅){魏³-<i>Ni>,<i>Ci>^a,<i>Ci>^b-C^a(CH₂C^bH₂)(鈺怌H-<i>oi>-C₅H₄N)}{PⁱPr₂[C(Me)鈺怌H₂]}]PF₆ (5), as a consequence of the oxidative addition of one of the C(sp²)鈥揅(sp³) bonds of the cyclopropane unit of the substrate to the osmium atom, along with 6, a diastereomer of 4. Complexes 3鈥?b>5 have been characterized by X-ray diffraction analysis. DFT calculations suggest that all of the reaction products are derived from a common key 1-osma-2-azacyclopent-3-ene intermediate (D).