N-甲基哌嗪作为环型二级胺在Stork反应中的应用

在Stork烯胺酰化反应中,通常需添加一个三级胺以中和反应中生成的氯化氢。产物常是液体或低熔点固体,不易提纯、析离。本文使用N-甲基哌嗪代替吗啉等常用的环状仲胺,考察其中的三级胺基能否起到外加三级胺的作用,并使酰化产物(Ⅲ)形成便于离析的盐酸盐结晶。我们以N-甲基哌嗪的环戊酮和环己酮烯胺为代表进行了乙酰化和苯甲酰化,析离了单酰基化产物Ⅲ(_a1),Ⅲ_a2和Ⅲ_b1及其相应的水解产物Ⅳ_a1,Ⅳ_a2,Ⅳ_b1和Ⅳ_b2;还得到了三个二酰基化产物。

STORK ACYLATION WITH N-METHYLPIPERAZINE AS THE AMINE COMPONENT IN THE FORMATION OF ENAMINES

Instead of usual cyclic secondary amines such as morph'oline etc., the N-metlylpiperazine was used in the Stork enamine acylation reactions and the following facts were found:1.The external neutralizer, such as TEA, used in usual procedure cannot be added now because a tertiary amine group is present in the N-methylpiperazine ring, but the yields of acylated enamines are less than that where TEAis added.2. The isolation of acylated enamine hydrochlorides is still difficul't for these hydrochlorides are h'ydroscopic and decompose readily on standing.3. In acylation reactions the diacylated products are also formed.