Amination with 3-acetoxyaminoquinazolin-4-(3H)ones: Preparation of α-aminoacid esters by reaction with silyl ketene acetals followed by N-N bond cleavage

Article abstract of DOI:10.1016/S0040-4020(01)90382-5

Solutions of 3-acetoxyaminoquinazoline (5) react with enol ethers and silyl ketene acetals to give α-aminoaldehyde α-aminoketone or α-aminoacid derivatives. Acylation of the exocyclic nitrogen in these derivatives, as a preliminary to reductive N-N bond cleavage, could only be accomplished by indirect means. Samarium diiodide, however, effected the reduction of this N-N bond without the necessity for N-acylation. Solutions of the corresponding enantiopure 3-acetoxyaminoquinazolinone (34) brought about the disastereoselective amination of the prochiral silyl ketene acetal (15) and reductive N-N bond cleavage of the major disastereoisomer lead to enantiopure 2-phenylalanine methyl ester.