Dimethylaminoalkyl and Methoxyalkyl Substituted Tetramethylcyclopentadienes: Synthesis of Novel Polydentate Ligands
作者:Peter Jutzi、Jürgen Dahlhaus
DOI:10.1055/s-1993-25921
日期:——
The synthesis of new tetramethylcyclopentadienes with a further functionalized carbon side chain, X(CH2)nC5Me4H (X = Cl, NMe2, OMe; n = 1, 2), is described. Treatment of 2-chloro-1-dimethylaminoethane with potassium tetramethylcyclopentadienide leads to the formation of a mixture of [2-(N,N-dimethylamino)-ethyl]tetramethylcyclopentadienes 3. Similarly, the reaction of 2-chloro-1-(p-toluenesulfonyl)ethane with lithium tetramethylcyclopentadienide yields a mixture of (2-chloroethyl) tetramethylcyclopentadienes 5. Due to geminal disubstitution, no isomers with an allylic hydrogen atom are present. Dicondensation of heteroatom-substituted esters, Me2N(CH2)nCO2R and MeO(CH2)nCO2R (n = 1, 2), with 2-butenyllithium gives rise to the corresponding dienoles 8a-d. Subsequent acid catalysed dehydration and ring closure leads to various new functionalized tetramethylcyclopentadienes 9a-d in good yields. Contrary to 3 and 5, only isomers with allylic hydrogen atoms are obtained. Thus, these compounds are suitable candidates for the synthesis of peralkylated cyclopentadienyl systems possessing an N- or O-substituted side chain.
报道了具有进一步功能化的碳侧链的新型四甲基环戊二烯的合成,X(CH2)nC5Me4H (X = Cl, NMe2, OMe; n = 1, 2)。用2-氯-1-二甲基氨基乙烷处理钾的四甲基环戊二烯化物,导致[2-(N,N-二甲基氨基)乙基]四甲基环戊二烯3的混合物形成。类似地,2-氯-1-(对甲苯磺酰)乙烷与锂的四甲基环戊二烯化物反应,产生(2-氯乙基)四甲基环戊二烯5的混合物。由于邻位双取代,不存在具有烯丙基氢原子的异构体。杂原子取代的酯,Me2N(CH2)nCO2R和MeO(CH2)nCO2R (n = 1, 2),与2-丁烯基锂的双缩合反应产生相应二烯醇8a-d。随后的酸催化脱水和环闭合反应,在良好产率下得到各种新的功能化四甲基环戊二烯9a-d。与3和5不同,仅得到具有烯丙基氢原子的异构体。因此,这些化合物是合成具有N-或O-取代侧链的全烷基化环戊二烯基系统的合适候选物。