Anti-Markovnikov 1,3-CH Addition of Allenes to Allenes: A Straightforward Method To Prepare Osmium鈥揇ienylcarbene Complexes

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• 作者：Ruth Castro-Rodrigo ; Miguel A. Esteruelas ; Ana M. L贸pez ; Enrique O帽ate
• 刊名：Organometallics
• 出版年：2012
• 出版时间：March 12, 2012
• 年：2012
• 卷：31
• 期：5
• 页码：1991-2000
• 全文大小：648K
• 年卷期：v.31,no.5(March 12, 2012)
• ISSN：1520-6041

文摘

One of the acetone molecules of the solvento complex [OsTp(魏¹-OCMe₂)₂(PⁱPr₃)]BF₄ (1; Tp = hydridotris(1-pyrazolyl)borate) is displaced by cyclohexylallene to give [OsTp(畏²-CH₂鈺怌鈺怌HCy)(魏¹-OCMe₂)(PⁱPr₃)]BF₄ (2). Treatment of 2 with a second molecule of cyclohexylallene leads to an 80:20 mixture of the conjugated (Z,Z)-osmahexatriene [OsTp{鈺怌H-(Z)-C(CH₂Cy)鈺怌H[畏²-(Z)-CH鈺怌HCy]}(PⁱPr₃)]BF₄ (3) and the (Z,Z)-dienylcarbene [OsTp{鈺怌H-(Z)-C[CH₂-畏²-(Z)-CH鈺怌HCy]鈺怌HCy}(PⁱPr₃)]BF₄ (4), as a result of an anti-Markovnikov 1,3-C鈥揌 addition of the coordinated allene of 2 to the CH₂鈺怌 double bond of the second allene molecule. In fluorobenzene at 85 掳C, 3 evolves into the hydride-(E,E)-dienylcarbyne [OsHTp{鈮-(E)-C(CH₂Cy)鈺怌H[(E)-CH鈺怌HCy]}(PⁱPr₃)]BF₄ (5), whereas 4 isomerizes into the (E,Z)-dienylcarbene [OsTp{鈺怌H-(E)-C[CH₂-畏²-(Z)-CH鈺怌HCy]鈺怌HCy}(PⁱPr₃)]BF₄ (6). Complex 2 also reacts with ethyl carboxylateallene. In dichloromethane at room temperature, the reaction gives [OsTp{鈺怌H-(Z)-C[CH₂-畏²-(Z)-CH鈺怌HCO₂Et]鈺怌HCy}(PⁱPr₃)]BF₄ (7), which isomerizes into [OsTp{鈺怌H-(E)-C[CH₂-畏²-(Z)-CH鈺怌HCO₂Et]鈺怌HCy}(PⁱPr₃)]BF₄ (8) in fluorobenzene at 85 掳C. Treatment of 7 with NaOMe yields OsTp{(E)-CH鈺怌[CH鈺?img src="/templates/jsp/_style2/_achs/images/tiebar-above-start.gif" class="tbAbove" alt="tiebar above start"/>C(CH₂)₄CH₂]CH₂-畏²-(Z)-CH鈺怌HCO₂Et)(PⁱPr₃) (9). The addition of HBF₄路OEt₂ to 9 gives 8.