The given synthesis pathway describes the formation of two dipeptides - Boc-Leu-Gly-OBzl and Bzl-Gly-Leu-OBoc.
Boc-Leu-Gly-OBzl is formed by first treating leucine with (BoC)2O, which converts the carboxyl group of leucine into its corresponding Boc ester. Separately, glycine is treated with benzyl alcohol/acid, which forms the intermediate benzyl glycinate. This intermediate is then reacted with Boc-leucine in the presence of DCC, which results in the formation of Boc-Leu-Gly-OBzl.
On the other hand, Bzl-Gly-Leu-OBoc is formed by first treating glycine with benzyl alcohol/acid, which forms the intermediate benzyl glycinate. This intermediate is then reacted with Boc-leucine in the presence of DCC, which results in the formation of Boc-Gly-Leu-OBzl. Finally, this dipeptide is treated with trifluoroacetic acid, which removes the Boc protecting group from the N-terminal end of the molecule, and then with aqueous NaOH, which removes the Bzl protecting group from the C-terminal end of the molecule, resulting in the formation of Bzl-Gly-Leu-OBoc.
Therefore, the dipeptide formed in the given synthesis pathway depends on the order in which the two intermediates (benzyl glycinate and Boc-leucine) are reacted with each other.