A P-chirogenic β-aminophosphine synthesis by diastereoselective reaction of the α-metallated PAMP–borane complex with benzaldimine

Jean-Michel Camus (1) , Jacques Andrieu (1) , Philippe Richard (1) , Rinaldo Poli (2) , Christophe Darcel (1) , Sylvain Jugé (1)

1 LSEO - Laboratoire de Synthèse et Electrosynthèse Organométalliques
2 LCC - Laboratoire de chimie de coordination

The diastereoselective synthesis of a P-chirogenic β-aminophosphine ligand with carbon–carbon bond formation of the ethano bridge in a 3:1 ratio via reaction of an α-metallated P-chirogenic phosphine borane with a benzaldimine is described. The diastereoselectivity is attributed to a transition state where the lithium cation chelates the phosphine borane carbanion and the nitrogen of the imine and the attack of the C@N occurs on the face opposite to the P–B bond, due to its interaction with the antibonding P–B bond. The major diastereoisomeric β-aminophosphine borane was then separated and decomplexed into the corresponding β-aminophosphine under neutral conditions and without epimerization by heating at reflux in EtOH. This synthesis offers a short hemisynthetic route to the P-chirogenic β-P,N-ligands, by bridge formation starting from methylphosphine boranes. The diastereoselective synthesis of a P-chirogenic β-aminophosphine ligand with carbon–carbon bond formation of the ethano bridge is described in three steps, via a key reaction of the α-metallated P-chirogenic phosphine borane with a benzaldimine.

Mots clés: Aminophosphine; Borane; Chiral phosphorous; Asymmetric synthesis

Domaines: Chimie de coordination

Jean-Michel Camus, Jacques Andrieu, Philippe Richard, Rinaldo Poli, Christophe Darcel, et al.. A P-chirogenic β-aminophosphine synthesis by diastereoselective reaction of the α-metallated PAMP–borane complex with benzaldimine. Tetrahedron: Asymmetry, 2004, 15 (13), pp.2061-2065. ⟨10.1016/j.tetasy.2004.05.031⟩. ⟨hal-03280580⟩