Stereoselective formation of a 2'(3')-aminoacyl ester of a nucleotide

Reaction of DL-serine and adenosine-5-phosphorimidazolide in the presence of adenosine-5'-(O-methylphosphate) and imidazole resulted in the stereoselective synthesis of the aminoacyl nucleotide ester 2'(3')-O-seryl-adenosine-5'-(O-methylphosphate). The enantiomeric excess of D-serine incorporated into 2'(3')-O-seryl-adenosine-5'-(O-methylphosphate) was about 9%. Adenylyl-(5'----N)-serine and an unknown product also incorporated an excess of D-serine; however, serylserine showed an excess of L-serine. The relationship of these results to the origin of the biological pairing of L-amino acids and nucleotides containing D-ribose is discussed.