UNUSUAL AMINO-ACIDS .1. ASYMMETRIC-SYNTHESIS OF FURYLALANINE DERIVATIVES

Nonproteinogenic amino acids are valuable active compounds from their pharmacological and biochemical effects and also as novel building blo cks for peptides. The preparation of furylalanine derivatives by asymm etric hydrogenation is described. Amino-phosphine-phosphinite-rhodium complexes catalyzed the hydrogenation of the prochiral dehydroamino ac id precursors in high rate and with enantioselectivities of 70-90% ee. Substrate-catalyst ratios up to 2,000 can be used depending on the ca talyst applied. The procedure turns out to be suitable for larger scal e preparations.