Chiral aminal termplates 61. Diastereoselectivity of hydrazone alkylation. Asymmetric synthesis of α-aminoaldehydes
摘要:
Glyoxal is efficiently transformed into the chiral aminals bearing the hydrazone functionality 2a and 2b. These compounds react under complete diastereocontrol with various organolithium reagents, affording chiral hydrazines 3-9. Reduction with Raney nickel leads to aminal protected alpha-aminoaldehydes, which, in turn, are easily hydrolyzed to the free chiral aldehydes (after tBoc protection of the amine).