A Zintl Cluster for Transition Metal-Free Catalysis: C═O Bond Reductions

Abstract

The first fully characterized boron-functionalized heptaphosphide Zintl cluster, [(BBN)P7]2– ([1]2–), is synthesized by dehydrocoupling [HP7]2–. Dehydrocoupling is a previously unprecedented reaction pathway to functionalize Zintl clusters. [Na(18-c-6)]2[1] was employed as a transition metal-free catalyst for the hydroboration of aldehydes and ketones. Moreover, the greenhouse gas carbon dioxide (CO2) was efficiently and selectively reduced to methoxyborane. This work represents the first examples of Zintl catalysis where the transformation is transition metal-free and where the cluster is noninnocent.

Mapping boron catalysis onto a phosphorus cluster platform

“…16,32,33 Very recently, we have reported on the first transition-metal free Zintl catalysis with a boron-functionalized [P 7 ] cluster, which was also found to be noninnocent in the transformation. 34 Here we tether boranes to a heptaphosphane cluster and use them in Lewis acid catalysis (Fig. 1).…”

“…16,32,33 Very recently, we have reported on the first transition-metal free Zintl catalysis with a boron-functionalized [P 7 ] cluster, which was also found to be noninnocent in the transformation. 34…”

A robust Zintl cluster for the catalytic reduction of pyridines, imines and nitriles

“…Further, in our previous stoichiometric studies between [Na(18-c-6)] 2 [1] and HBpin there was no evidence of HBBN formation. 34 Therefore, we do not expect 2b′ to formed after catalysis.…”

Reactivity of tetrel functionalized heptapnictogen clusters towards heteroallenes

“…17,18 Recently, we have found that boron-functionalized [P 7 ] cages can be applied as transition-metal free catalysts in hydroboration reactions. 19,20 Heteroallene insertion between labile non-cluster tetrelpnictogen bonds has previously been reported. [21][22][23][24][25][26] In 2022 we found for the first time this reactivity with Zintl-derived clusters.…”

“…17,18 Recently, we have found that boron-functionalized [P 7 ] cages can be applied as transition-metal free catalysts in hydroboration reactions. 19,20…”