Alkyleisen‐und Alkylcobalt‐Reagenzien, VII. Über die Substitution des Halogens von Alkenylchloriden, Alkenylfluoriden und Alkinylhalogeniden durch Reagenzien des Typs R4MLi2 (MFe, Co)
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Title:
Alkyleisen‐und Alkylcobalt‐Reagenzien, VII. Über die Substitution des Halogens von Alkenylchloriden, Alkenylfluoriden und Alkinylhalogeniden durch Reagenzien des Typs R4MLi2 (MFe, Co)
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<jats:p><jats:bold>Alkyliron and Alkylcobalt Reagents, VII<jats:sup>[1]</jats:sup>. – On the Substitution of the Halogen of Alkenyl Chlorides, Alkenyl Fluorides, and Alkynyl Halides by Reagents of the Type R<jats:sub>4</jats:sub>MLi<jats:sub>2</jats:sub> (MFe, Co)</jats:bold></jats:p><jats:p>Me<jats:sub>4</jats:sub>FeLi<jats:sub>2</jats:sub> and Me<jats:sub>4</jats:sub>CoLi<jats:sub>2</jats:sub>, which are favourable reagents for the substitution of Br in alkenyl bromides<jats:sup>[1–4]</jats:sup>, also proved to be favourable for the substitution of the halogen in alkenyl chlorides (yields 68–99%; nearly complete retention of configuration in the case of Me<jats:sub>4</jats:sub>FeLi<jats:sub>2</jats:sub>), β1‐fluorostyrene (best yield 92%), and 1‐fluoronaphthalene (best yield 47%). Me<jats:sub>4</jats:sub>FeLi<jats:sub>2</jats:sub> differentiates between various alkenyl chlorides in 1:1 competition experiments better than Me<jats:sub>4</jats:sub>CoLi<jats:sub>2</jats:sub> and is the optimal reagent for the substitution of halogen in 1‐chloro‐2‐phenylethyne (<jats:bold>12</jats:bold>), 1‐bromo‐2‐phenylethyne (<jats:bold>13</jats:bold>), and 1‐chloro‐3‐phenoxypropyne (<jats:bold>15</jats:bold>) by methyl (yields 70, 46, and 80%, respectively). Substitution of the halogen in <jats:bold>12</jats:bold> by the <jats:italic>n</jats:italic>1‐butyl, <jats:italic>n</jats:italic>1‐octyl, and phenyl residue is better achieved by the catalytic systems RMgBr + 2.5 mol % FeCl<jats:sub>2</jats:sub> (R<jats:italic>n</jats:italic>Bu, <jats:italic>n</jats:italic>Oct, Ph; yields 75, 63, and 96%, respectively) than by the reagents <jats:italic>n</jats:italic>Bu<jats:sub>4</jats:sub>FeLi<jats:sub>2</jats:sub>, <jats:italic>n</jats:italic>Bu<jats:sub>4</jats:sub>Fe(MgBr)<jats:sub>2</jats:sub>, <jats:italic>n</jats:italic>Oct<jats:sub>4</jats:sub>Fe(MgBr)<jats:sub>2</jats:sub>, or Ph<jats:sub>4</jats:sub>Fe(MgBr)<jats:sub>2</jats:sub> (yields 18–28%).</jats:p>