R. Kuwano et al., Enantioselective construction of quaternary alpha-carbon centers on alpha-amino phosphonates via catalytic asymmetric allylation, ORG LETT, 1(6), 1999, pp. 837-839
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Asymmetric allylation of alpha-acetamido beta-keto phosphonates was promote
d, in the presence of potassium tert-butoxide as a base, by a palladium cat
alyst prepared from [Pd(pi-allyl)(cod)]BF4 and (R)-BINAP and gave the corre
sponding alpha-alkyl alpha-amino phosphonic acid derivatives with 65-88% ee
. Diastereoselective reduction of the carbonyl group in the product was acc
omplished by NaBH4 or BU4NBH4. The diastereoselection in the reduction was
reversed by choice of solvent.