Cobalt(II)chloride catalysed cleavage of ethers with acyl halides: Scope and mechanism
作者:Javed Iqbal、Rajiv Ranjan Srivastava
DOI:10.1016/s0040-4020(01)96041-7
日期:1991.5
Cobalt (II) chloride in acetonitrile catalyses the cleavage of a wide variety of ethers with acyl halides under mild conditions to give the corresponding esters in good yields. Acyclic aliphatic ethers are cleaved to the corresponding ester and chlorides whereas the cyclic aliphatic ethers give rise to the ω-chloroesters. The benzyl ethers can be converted to the corresponding esters along with the
乙腈中的氯化钴(II)在温和的条件下催化多种醚与酰基卤的裂解,从而以高收率得到相应的酯。无环脂族醚裂解成相应的酯和氯化物,而环脂族醚产生ω-氯代酯。苄基醚可与苄基氯和苄基乙酰胺一起形成相应的酯。烯丙基和苄基醚裂解的比较研究表明,苄基醚可以在烯丙基醚存在下选择性裂解。可以以高度区域选择性的方式将环氧乙烷酮裂解为相应的β-氯代酯。乙烯基醚经历sp 2在这些条件下的-杂化的碳-氧键裂解。基于产物分析,讨论了涉及电子转移,随后进行O-酰化以及氯离子对S N 1或S N 2的攻击的机理。
Silver iodide mediated amination reaction of allylic chlorides with lithium bis(trimethylsilyl)amide: a new synthetic method of N,N-disilylallylamines via lithium amide argentates
The nucleophilic substitution reaction of allylic chlorides with lithium bis(trimethylsilyl)amide (1) in the presence of silver halides has been studied in detail. Silver iodide (AgI) was found to be most effective for facilitation of the amination reaction. The reaction of alkyl-substituted allylic chlorides proceeded smoothly in S(N)2 fashion to give N,N-disilylallylamines in high yields when 0.1 or 0.5 equiv of AgI was used as an additive, whereas a stoichiometric amount of AgI was indispensable in the reaction of allylic chlorides having a phenyl group. The reaction of geranyl or neryl chloride proceeded with retention of configuration of the C=C bond to give only one isomer 4 or 5, respectively. The oxygen-containing functional groups and chlorine remained intact during the reaction. The reaction of alpha-silylmetallyl chloride 17 proceeded in an S(N)2' manner to afford (Z)-allylamine 18. So as to disclose the active species in the AgI-mediated reaction, the variable low-temperature C-13 NMR experiments using the mixture of AgI and 1 in THF have been performed. It has been suggested that lithium amide argentates such as (Me3Si)2NAg(I)Li (20) and [(Me3Si)2N]2Ag(I)Li2 (21) are formed in the reaction mixture, and the nucleophilicity and basicity of 1 are controlled by forming these species.