A set of hybrid P-stereogenic phosphine-diamidophosphite ligands based on the Betti base backbone has been synthesized. The ligands possess five chiral centers including the P-chirality in both the phosphorus atoms....

The enantioselective hydrogenation of cyclic enamides has been achieved using an earth‐abundant cobalt‐bisphosphine catalyst. Using CoCl2/(S,S)‐Ph‐BPE, several trisubstituted carbocyclic enamides were reduced with high activity and excellent enantioselectivity (up to 99 %) to the corresponding saturated amides. The methodology can be extended to the synthesis of chiral amines by base hydrolysis of the hydrogenation products. Preliminary mechanistic investigations reveal the presence of a high spin cobalt (II) species in the catalytic cycle. We propose that the hydrogenation of the carbon‐carbon double bond proceeds via a sigma‐bond‐metathesis pathway.

What is the most significant result of this study? Our paper reports on novel P-N-P-containing compounds which can be prepared by reducing N,N-bis{chloro(aryl)-phosphino}-amines. Due to the variation of the substituents at the phosphorus or nitrogen centers, the solvents and reducing agents, we were able to develop selective syntheses for several cyclic compounds. We consider the formation of new PN rings as the essence of this paper.

Different N,N‐bis[chloro(aryl)phosphino]amines were synthesized and characterized. The synthesized compounds were tested as ligands in the Cr‐catalyzed oligomerization of ethene. The effect of the successive increase of the steric bulk either at one of the P substituents or at the N center on the product distribution of the oligomerization reaction was examined. We found a highly active and selective trimerization system with purities of the hexene fraction up to 99.9 % for 1‐hexene. Furthermore, we suppose an in situ methylation of the chlorinated ligands into the corresponding N,N‐bis[methyl(aryl)phosphino]amines.