When an aqueous solution of urea and pyruvic acid was heated under reflux in the presence of formic acid, 2-ureidopropionic acid, that is, N-carbamoylalanine, was obtained in the yield of about 35%. This compound was considered to be formed by Leuckart reaction, in which N-alkylation is achieved by formic acid reduction of primarily formed Schiff base of a ketone and an amine. It had been believed that Leuckart reaction of amides or urea with formaldehyde does not afford N-alkylated products. Although the intended reaction practically failed to proceed below 100℃, we found that this reaction can be applied to the alkylation of urea at 100 and 120℃. This study proposed a novel pathway leading to formation of alanine from precursors, which are likely present on the primitive Earth. The formation of N-carbamoylalanine is of another significance, since we found in a separate experiment that it undergoes thermal polymerization.