Vj. Blazis et al., REACTIONS OF CHIRAL PHOSPHORUS-ACID DIAMIDES - THE ASYMMETRIC-SYNTHESIS OF CHIRAL ALPHA-HYDROXY PHOSPHONAMIDES, PHOSPHONATES, AND PHOSPHONIC-ACIDS, Journal of organic chemistry, 60(4), 1995, pp. 931-940
Addition of aldehydes to the anions of chiral phosphorous acid diamide
s in THF solution gave a-hydroxy phosphonamides in good yield. The dia
stereoselectivity was strongly dependent upon the diamide used and ran
ged from poor to good. The phosphorous acid diamides 2a and 2b (R(1) =
-(CH2)4-,R(2) = CH(2)Ph and CH(2)CMe(3), respectively) gave the best
selectivity, and their reactions with a range of aldehydes were studie
d. Diamide 2b consistently gave good selectivities, whereas diamide 2a
was only moderately selective. Aromatic, aliphatic, and unsaturated a
ldehydes are tolerated under the reaction conditions. The phosphonamid
es were hydrolyzed with aqueous HCl in dioxane to give a-hydroxy phosp
honic acids. While direct methanolysis of the phosphonamides was unsuc
cessful, methylation of the phosphonic acids with diazomethane gave al
pha-hydroxy dimethylphosphonates.