Asymmetric synthesis of uncommon α-amino acids by diastereoselective alkylations of a chiral glycine equivalent

Article abstract of DOI:10.1016/0957-4166(96)00212-1

For the purpose of practical preparations of a variety of enantiomerically pure uncommon α-amino acids, alkylations of the chiral glycine equivalent 5, which possesses axially chiral binaphthol as an auxiliary, with several electrophiles were investigated. The alkylation proceeded smoothly in satisfactory chemical yield with high diastereo-selectivities to give protected α-amino acid derivatives. The free hydroxyl group of the auxiliary played an important role for the induction of diastereoselectivity. Using (S)-1,1'-binaphthalene-2,2'-diol as a chiral auxiliary, D-α-amino acid derivatives having the unnatural (R)-configuration were predominantly obtained. Some of the alkylated products were converted into free non- proteinogenic D-α-amino acids.