P-Stereogenic diamondoid phosphines

Abstract

Despite diamondoid phosphines have found many synthetic applications and are even available commercially the chemistry of chiral diamondoid phosphines remains largely unexplored. Aim. To develop the convenient preparative method for the preparation of sterically-congested P-stereogenic secondary diamodoidyl phosphines as potential organocatalysts and ligands in the asymmetric synthesis. Results and discussion. A convenient method for the synthesis of P-stereogenic diamondoid phosphines with high yields through the phosphorylation of hydroxydiamondoids in trifluoroacetic acid followed by the reduction of the corresponding asymmetric chlorophosphonates has been proposed. The secondary phosphines obtained form stable complexes with borane that can be used to separate diamondoid phosphines into enantiomers. Experimental part. The experimental procedures for the preparation of 1- and 4-diamantyl-1-adamantyl- and phenylphosphines were developed; the structures of new compounds were confirmed by NMR and HRMS spectral data. Conclusions. A number of P-stereogenic mixed diamondoidylaryl phosphines and the secondary phosphines containing exclusively diamondoid substituents has been prepared. A degree of steric bulkiness is determined by the combination of diamondoid substituents around a phosphorus atom where 1-diamantyl derivatives are the most sterically-congested. The compounds obtained are potential ligands in asymmetric catalysis.

Keywords

• phosphine borane complexes
• 1-adamantyldiamantylphosphine
• 4-adamantyldiamantylphosphine
• 1-phenyldiamantylphosphine
• 4-phenyldiamantylphosphine
• p-stereogenic phosphines