Asymmetric Hydrophosphination of Nitroalkenes

Significance

An organocatalytic entry to chiral phosphines has been developed. The method employs a catalyst which combines structural motifs of cinchona alkaloids (activating the phosphine) with an electron-poor thiourea moiety (presumably binding to the nitro group). It yields compounds containing the desired phosphine as well as a nitro group, which can be further manipulated. The nitrophosphines are directly converted in one pot into the borane adducts for increased stability and simplified purification. The product purity can be dramatically improved by recrystallization, which allows to obtain the enantiopure compounds.