Further studies focused on reactions of derivatives of L-serine, L-threonine, L-allo-threonine, and o-hydroxyaniline (14 -17, 87-94%), which proceeded with retention of configuration at the β-carbon in threonine and allo-threonine (Scheme 3). The generation of oxazoline 18 (93%) shows the high selectivity of the catalyst with a C1 glycosyl alcohol which is prone to elimination and formation of a glycal byproduct. Similarly, the synthesis of oxazoline 19 in high yield was achieved despite the bulky nature of the diphenylacetic acid derivative. Furthermore, a Boc protected L-threonine pseudoproline dipeptide was cyclized into 20 in 70% yield. 20 was produced as a single diastereomer, despite being prone to epimerization. The stereochemical integrity of the α position in oxazoline 21, derived from a trifluoroacetamide-functionalized dipeptide, was difficult to retain due to the electron withdrawing effect of the trifluoroacetamide, which increases epimerization. Despite these effects, 21 with a dr of 1.00:0.45 was produced in appreciable yield (71%). To reduce the amount of epimerization, we decided to shorten the reaction time to 2.5 h and achieved a dr of 1.00:0.10 albeit in a reduced yield (36%). In some substrates (22, 28 -29), a coordinating primary or secondary amide may interfere with the Mo(VI) catalyst but in our hands the corresponding oxazolines were synthesized in 55-95% yield.