Homochiral cyclopentane-based C1-symmetric P,P ligands C5H8(PPh2)(PR2) from C2-symmetric C5H8(PCl2)2

Treatment of 1,2-trans-C5H8(PCl2)2 with 1,2-C2H4(NHPr-i)2 gave the C2-symmetric perhydro-1,6,2,5-diazaphosphocine C5H8{P(Cl)N(Pr-i)CH2}2-cyclo, which produced dissymmetric C5H8(PPh2){P[N(Pr-i)CH2]2-cyclo} on further reaction with PhMgBr. Cleavage of the PN bonds with gaseous HCl afforded C5H8(PPh2)(PCl2), which was converted to C5H8(PPh2){P(OPh)2}2 by reaction with phenol. All chiral P,P derivatives were obtained as racemates as well as resolved (1R,2R)- and (1S,2S)-enantiomers.