Chiral phosphine ligands from amino acids. II [1] a facile synthesis of phosphinoserines by nucleophilic phosphination reactions - X-ray structure analyses of Ar2P-CH2CH(NHBOC)(COOMe) (Ar = Ph, m-xylyl)

Phosphino derivatives of serine R2P-CH2-CH(NHBOC)(COOMe) (2a-2d) have been obtained in high yield by nucleophilic phosphination of N-(tert.butoxycarbo nyl)-3-iodo-L-alanine methylester with secondary phosphines R2PH (R=Ph, tol yl, 3,5-xylyl, cyclohexyl) in DMF using potassium carbonate as the base. De protection of 2b with HCl affords the amino acid ester hydrochloride [2-Tol (2)P-CH2-CH(NH3)(COOMe)]Cl-+(-) (3a). The X-ray structures of 2a (space gro up P2(1/n)) and 2c (space group P (1) over bar) have been determined. The t wo enantiomers of 2a or 2c are interconnected by N-H . . .O hydrogen bridge s forming dimers in the solid state.