DERIVATIVES OF 2-AMINO-2'-DIPHENYLPHOSPHINO-1,1'-BINAPHTHYL (MAP) ANDTHEIR APPLICATION IN ASYMMETRIC PALLADIUM(0)-CATALYZED ALLYLIC SUBSTITUTION

(R)-(+)-2-Amino-2'-hydroxy-1,1'-binaphthyl (NOBIN, 5) can be readily c onverted into a series of novel N,N-disubstituted aminophosphines 9 an d 23-25. The N,N-dimethyl derivative (R)-9 (MAP) was prepared via a se quence involving reductive alkylation with CH2O and NaBH4 (5 --> 6), P d-(O)-catalyzed coupling of the corresponding triflate with Ph2P(O)H ( 7 --> 8), and reduction of the resulting phosphine oxide with Cl3SiH ( 8 --> 9). Variation of this scheme was required for the preparation of 23-25 as the phosphinylation failed in the presence of bulky N substi tuents; the N-protected triflate 17 was first coupled with Ph2P(O)H, a nd the resulting phosphine oxide 18 was reduced with Cl3SiH to give th e aminophosphine 19, which was then subjected to reductive alkylation with individual ketones and NaBH4. The new P,N-binaphthyls thus obtain ed (23-25 and 9) were utilized as chiral ligands in Pd(O)-catalyzed al lylic substitution. The enantioselectivites obtained for racemic 1,3-d iphenylprop-2-en-1-yl acetate (+/-)-26 and malonate nucleophiles, whic h gave (S)-(-28, (R)-(+)-29, and (R)-(+)-30 as the respective products tin up to 71-73% ee at room temperature with Cs2CO3 in CH2Cl2 and 9 o r 23 as a ligand), are interpreted in terms of the chelated transition state 37 and preferential attack at the allylic terminus that is tran s with respect to the phosphorus acceptor atom.