Efficient Preparation of α,α-Dialkyl-α-(phenylselanyl)acetates and α,β-Unsaturated Esters from the Corresponding α,α-Dialkyl-α-cyanoacetates by a Lithium Naphthalenide Induced Reductive Selenenylation Process
作者:Jia-Liang Zhu、Yen-Chun Ko
DOI:10.1055/s-2007-990884
日期:2007.12
array of α,α-dialkyl-α-(phenylselanyl)acetates has been synthesized very efficiently from readily available a,a-dialkyl-a-cyanoacetates, by use of lithium naphthalenide induced reductive α-selenenylation as a key operation. Moreover, the selanyl esters thus generated in situ could be converted further, in a one-pot treatment with hydrogen peroxide and acetic acid, into the corresponding α,β-unsaturated
Reaction of a zero-valent ruthenium complex [Ru(cot)(cod)] 1 (cod = 1,5-cyclooctadiene; cot = 1,3,5-cyclooctatriene) with alkyl cyanoacetate in the presence of mono- and bi-dentate tertiary phosphines gave a series of hydrido(enolato)ruthenium(II) complexes: mer-[RuH(NCCHCO2Et)(NCCH2CO2Et)(PPh3)3] 2; trans-[RuH(NCCHCO2Et)(cod)(dppe)] 3 (dppe = Ph2PCH2CH2PPh2); trans-[RuH(NCCR1CO2R2)(dppe)2] (R1 = H, R2 = Et 4a: or Pri 4b; R1 = Me, R2 = Et 4c) and trans-[RuH(NCCMeCO2Et)(PMePh2)4] 5. The molecular structure of 3 shows that the enolato ligand co-ordinates to the ruthenium centre via the cyano group in an octahedral geometry. These hydrido(enolato)ruthenium(II) complexes catalyse Michael and Knöevenagel reactions under neutral and mild conditions.
零价钌配合物[Ru(cot)(cod)] 1(cod = 1,5-环辛二烯;cot = 1,3,5-环辛三烯)与氰乙酸烷基酯在单齿和双齿叔膦存在下发生反应,生成了一系列氢rido(enolato)钌(II)配合物:mer-[RuH(NCCHCO2Et)(NCCH2CO2Et)(PPh3)3]2;trans-[RuH(NCCHCO2Et)(cod)(dppe)]3(dppe = Ph2PCH2CH2PPh2);trans-[RuH(NCCR1CO2R2)(dppe)2](R1 = H,R2 = Et 4a:或 Pri 4b;R1 = Me,R2 = Et 4c)和反式-[RuH(NCCMeCO2Et)(PMePh2)4] 5。3 的分子结构显示,烯醇配体通过氰基以八面体几何形状与钌中心配位。这些氢rido(enolato)钌(II)配合物在中性和温和条件下可催化迈克尔反应和 Knöevenagel 反应。