Activation and Substitution of 1‑Ferrocenylalkylamines with Allenones: Application to Three-Component Synthesis of 4‑(1-Ferrocenyl­alkyl)­pyrazoles

A one-pot,
two-step three-component synthesis of 4-(1-ferrocenylalkyl)­pyrazoles
has been developed involving activation and substitution of 1-ferrocenylalkylamines
with allenones under mild conditions. A range of 1-ferrocenylalkylamines
reacted with allenones in the presence of dipicolinic acid at room
temperature without extrusion of air and moisture, and the resulting
crude products were treated with hydrazine to afford structurally
diverse 4-(1-ferrocenylalkyl)­pyrazoles in moderate to good yields.
Moreover, the three-component reaction was successfully extended to
an enantioenriched α-ferrocenylbenzylamine with complete retention
of configuration.

本研究开发了一种两步三组分一锅法合成策略，用于制备4-(1-二茂铁基烷基)吡唑（4-(1-ferrocenylalkyl)pyrazoles）类化合物，该过程通过在温和条件下使1-二茂铁基烷基胺（1-ferrocenylalkylamines）与联烯酮（allenones）发生活化与取代反应得以实现。多种1-二茂铁基烷基胺可在室温、无需排除空气与水汽的条件下，于吡啶二羧酸（dipicolinic acid）存在时与联烯酮发生反应；所得粗产物经肼（hydrazine）处理后，即可得到结构多样的4-(1-二茂铁基烷基)吡唑类化合物，产率中等至良好。此外，该三组分反应可成功拓展至对映富集的α-二茂铁基苄胺（α-ferrocenylbenzylamine）底物，且反应过程中完全保留底物构型。