A process for preparing α,β-unsaturated aldehydes of the general formula (I)
in which R', R2 and R" are independently a hydrogen atom, or an alkyl or alkenyl group with or without being substituted with a lower acyloxy group. The aldehyde of the general formula (I) is prepared by reaction between an allylic chloride of the following general formula (Ila)
in which R1, R2 and R3 have, respectively, the same meanings as defined above, and an amide oxide selected from the group consisting of tri(lower alkyl)amine N-oxides of the formula,
in which R4 represents a lower alkyl group having from 2 to 4 carbon atoms, and N-lower alkylmorpholine N-oxides of the following formula
in which R5 represents a lower alkyl group having from 1 to 4 carbon atoms. Alternatively, the aldehyde of the formula (I) is obtained by reaction between an allylic chloride of the following general formula (IIb)
in which R1, R2 and R3 have, respectively, the same meanings as defined above, and an amine oxide selected from the group consisting of tri(lower alkyl)amine N-oxides of the formula,
in which R4 has the same meaning as defined above, and N-lower alkylmorpholine N-oxides of the following formula
in which R5 has the same meaning as defined above, in the presence of an alkali metal iodide or a copper halide.
一种制备通式(I)的α,β-不饱和醛的工艺
其中 R'、R2 和 R "独立地为氢原子或烷基或烯基,可被或未被低级酰氧基取代。通式(I)的醛是由以下通式(Ila)的烯丙基
氯反应制备的
其中 R1、R2 和 R3 分别具有与上式定义相同的含义,和选自由式三(低级烷基)胺 N-氧化物组成的酰胺氧化物、
其中 R4 代表具有 2 至 4 个碳原子的低级烷基,以及下式的 N-低级烷基吗啉 N-氧化物
其中 R5 代表具有 1 至 4 个碳原子的低级烷基。另外,式 (I) 的醛是通过与下式通式 (IIb) 的烯丙基
氯反应得到的
其中 R1、R2 和 R3 分别具有与上式定义相同的含义,而氧化胺选自式(IIb)的三(低级烷基)胺 N-氧化物组成的组、
其中 R4 的含义与上式所定义的相同,以及下式的 N-低级烷基吗啉 N-氧化物
其中 R5 的含义与上述定义相同,在碱
金属
碘化物或卤化
铜存在下。