four cyclic dehydrodipeptides , cyclo ( -delta aminoacyl-l-ala- ) , in which aminoacyl is phe , apb ( 2-amino-4-phenylbutanoic acid ) , app ( 2-amino-5-phenylpentanoic acid ) and aph ( 2-amino-6-phenylhexanoic acid ) , were prepared by condensation of cyclo ( -n-ac-gly-n-ac-l-ala- ) with the corresponding aldehydes .
C0002563
delta
C0002520
amino